In some cases there is a difference between the two, we should always
be doing one or the other. For convenience, `type_cast` is still a
private method on type, so new types that do not need different behavior
don't need to implement two methods, but it has been moved to private so
it cannot be used accidentally.

For consistency with https://github.com/rails/rails/pull/15557

`@raw_attributes` should not contain the type-cast, mutable version of
the value.

With ActiveRecord::Properties, we now have a reasonable path for users
to continue to keep this behavior if they want it. This is an edge case
that has added a lot of complexity to the code base.

It appears that the only time that `quote` is called with a column,
but without first calling `type_cast` is when where is called with an
array. My previous pull request broke this behavior, without failing
tests. This adds a test for the only case I can think of that exercises
the `if column.type == :integer` branch of `quote` effectively.

It appears to have been used at some point in the past, but is no longer
used in any meaningful way. Whether a column is considered primary is
a property of the model, not the schema/column. This also removes the
need for yet another layer of caching of the model's schema, and we can
leave that to the schema cache.

consistent.

Example:

    author.posts == Post.where(author_id: author.id)
    # => true
      Post.where(author_id: author.id) == author.posts
    # => true

Fixes #13506

460eb83d cused `ActiveRecord::Base#==` to sometimes return `nil` in some cases,
this ensures we always return a boolean value. Also fixed a similar problem in
AR reflections.

This commit bring the famous ordinal Array instance methods defined
in ActiveSupport into ActiveRecord as fully-fledged finders.

These finders ensure a default ascending order of the table's primary
key, and utilize the OFFSET SQL verb to locate the user's desired
record. If an offset is defined in the query, calling #second adds
to the offset to get the actual desired record.

Fixes #13743.

This solves order depndent problems in `base_test.rb`. The leaked column
information crashed test cases using the `Weird` class later on:

```
  2) Error:
BasicsTest#test_group_weirds_by_from:
SyntaxError: /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:387: invalid hex escape
... attribute_before_type_cast("\x{A4CA}\x{A4DE}\x{A4A8}", *arg...
...                               ^
/Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:387: invalid hex escape
...te_before_type_cast("\x{A4CA}\x{A4DE}\x{A4A8}", *args)
...                               ^
/Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:387: invalid hex escape
...e_type_cast("\x{A4CA}\x{A4DE}\x{A4A8}", *args)
...                               ^
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:385:in `module_eval'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:385:in `define_proxy_call'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:294:in `block in define_attribute_method'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:285:in `each'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:285:in `define_attribute_method'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:252:in `block in define_attribute_methods'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:252:in `each'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:252:in `define_attribute_methods'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_methods.rb:72:in `block in define_attribute_methods'
    /Users/senny/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/mutex_m.rb:73:in `synchronize'
    /Users/senny/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/mutex_m.rb:73:in `mu_synchronize'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_methods.rb:69:in `define_attribute_methods'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_methods.rb:174:in `method_missing'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_assignment.rb:45:in `public_send'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_assignment.rb:45:in `_assign_attribute'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_assignment.rb:32:in `block in assign_attributes'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_assignment.rb:26:in `each'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_assignment.rb:26:in `assign_attributes'
    /Users/senny/Projects/rails/activerecord/lib/active_record/core.rb:458:in `init_attributes'
    /Users/senny/Projects/rails/activerecord/lib/active_record/core.rb:191:in `initialize'
    /Users/senny/Projects/rails/activerecord/lib/active_record/inheritance.rb:30:in `new'
    /Users/senny/Projects/rails/activerecord/lib/active_record/inheritance.rb:30:in `new'
    /Users/senny/Projects/rails/activerecord/lib/active_record/persistence.rb:33:in `create'
    test/cases/base_test.rb:646:in `test_group_weirds_by_from'
```

We can conditional define the tests depending on the adapter or
connection.

Lets keep the skip for fail tests that need to be fixed.

Revert "ActiveRecord::Base#<=> has been removed.  Primary keys may not be in order," -- will be replaced with a check to ensure that the keys used for comparison are integers, and only fail if they are not.

This reverts commit 6256734e.

Conflicts:
	activerecord/CHANGELOG.md

marshalling between processes does not work with an in-memory db.
This breaks the `test_sqlite3_mem` run (see stacktrace below).
After that failure most tests start to fail randomly.

```
/Users/senny/Projects/rails/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb:512:in `table_structure': Could not find table 'posts' (ActiveRecord::StatementInvalid)
	from /Users/senny/Projects/rails/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb:399:in `columns'
	from /Users/senny/Projects/rails/activerecord/lib/active_record/connection_adapters/schema_cache.rb:93:in `block in prepare_default_proc'
	from /Users/senny/Projects/rails/activerecord/lib/active_record/connection_adapters/schema_cache.rb:44:in `yield'
	from /Users/senny/Projects/rails/activerecord/lib/active_record/connection_adapters/schema_cache.rb:44:in `columns'
	from /Users/senny/Projects/rails/activerecord/lib/active_record/model_schema.rb:208:in `columns'
	from /Users/senny/Projects/rails/activerecord/lib/active_record/model_schema.rb:249:in `column_defaults'
	from /Users/senny/Projects/rails/activerecord/lib/active_record/locking/optimistic.rb:171:in `column_defaults'
	from /Users/senny/Projects/rails/activerecord/lib/active_record/core.rb:167:in `initialize'
	from /Users/senny/Projects/rails/activerecord/lib/active_record/inheritance.rb:27:in `new'
	from /Users/senny/Projects/rails/activerecord/lib/active_record/inheritance.rb:27:in `new'
	from /Users/senny/Projects/rails/activerecord/test/cases/base_test.rb:1368:in `block in test_marshal_between_processes'
	from /Users/senny/Projects/rails/activerecord/test/cases/base_test.rb:1366:in `fork'
	from /Users/senny/Projects/rails/activerecord/test/cases/base_test.rb:1366:in `test_marshal_between_processes'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest/test.rb:110:in `block (3 levels) in run'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest/test.rb:208:in `capture_exceptions'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest/test.rb:107:in `block (2 levels) in run'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest/test.rb:260:in `time_it'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest/test.rb:106:in `block in run'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest.rb:296:in `on_signal'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest/test.rb:280:in `with_info_handler'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest/test.rb:105:in `run'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest.rb:268:in `block (2 levels) in run'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest.rb:267:in `each'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest.rb:267:in `block in run'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest.rb:296:in `on_signal'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest.rb:285:in `with_info_handler'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest.rb:266:in `run'
	from /Users/senny/Projects/rails/activesupport/lib/active_support/test_case.rb:31:in `block in __run'
	from /Users/senny/Projects/rails/activesupport/lib/active_support/test_case.rb:31:in `map'
	from /Users/senny/Projects/rails/activesupport/lib/active_support/test_case.rb:31:in `__run'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest.rb:115:in `run'
	from /Users/senny/Projects/rails/.bundle/gems/minitest-5.0.8/lib/minitest.rb:46:in `block in autorun'
```

/cc @tenderlove

or even be numbers, so sorting by id doesn't make sense.  Please use `sort_by`
and specify the attribute you wish to sort with.  For example, change:

  Post.all.to_a.sort

to:

  Post.all.to_a.sort_by(&:id)

When the adapter is with prepared statement disabled and the binds array
is not empty the connection adapter will try to set the binds values and
will fail. Now we are checking if the adapter has the prepared statement
disabled.

Fixes #12023

This reverts commit 71ff7d9c.

Reason: I need to check with @jeremy if we can do this.

This reverts commit baf5f47b.

Reason: This is breaking the sqlite3 tests with a missing transacion.
Could not investigate right now.

cc @tenderlove

The visitor have to consume the bind parameters to make the statements
work when the prepared statement option is disabled.

Fixes #12023