Cannot call private methods in `@klass` against `CollectionProxy`
(inherites `Relation`) because using `public_send` in `method_missing`.

The current code base is not uniform. After some discussion,
we have chosen to go with double quotes by default.

This reverts commit 60c97012, reversing
changes made to 6a25202d.

Reason: Broken build

This triggers the JoinDependency work to reflect on the associations
and trigger an error as follows:

  ActiveRecord::ConfigurationError: Association named 'account' was
  not found on Company; perhaps you misspelled it?

Fix Company.of_first_firm joins association name

Should be `Company.joins(:accounts)` not `Company.joins(:account)`.

Do the same for Client.of_first_firm

* When tried to use `Company#accounts` test/models/company.rb I got:

```
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column:
accounts.company_id: SELECT COUNT(*) AS count_all, "companies"."firm_id"
AS companies_firm_id FROM "companies" INNER JOIN "accounts" ON
"accounts"."company_id" = "companies"."id" GROUP BY "companies"."firm_id"
```

* The refactor on Calculations class was just to simplify the code

`inverse_of` on through associations was accidently removed/caused to
stop working in commit f8d2899d which was part of a refactoring on
`ThroughReflection`.

To fix we moved `inverse_of` and `check_validity_of_inverse!` to the
`AbstractReflection` so it's available to the `ThroughReflection`
without having to dup any methods. We then need to delegate `inverse_name`
method in `ThroughReflection`. `inverse_name` can't be moved to
`AbstractReflection` without moving methods that set the instance
variable `@automatic_inverse_of`.

This adds a test that ensures that `inverse_of` on a `ThroughReflection`
returns the correct class name, and the correct record for the inverse
relationship.

Fixes #21692

If your STI class looks like this:

```ruby
class Company < ActiveRecord::Base
  self.store_full_sti_class = false

  class GoodCo < Company
  end

  class BadCo < Company
  end
end
```

The expectation (which is valid) is that the `type` in the database is saved as
`GoodCo` or `BadCo`. However, another expectation should be that setting `type`
to `GoodCo` would correctly instantiate the object as a `Company::GoodCo`. That
second expectation is what this should fix.

without replacement.

This error only happens when the foreign key is missing.

Before this fix the following exception was being raised:

    NoMethodError: undefined method `val' for #<Arel::Nodes::BindParam:0x007fc64d19c218>

Now the message is:

    ActiveRecord::UnknownAttributeError: unknown attribute 'foreign_key' for Model.

Related issue: #11939, #12084

This reverts commit 70d6e16f, reversing
changes made to ea4db3bc.

Seems to be a code merge done by mistake.

For example, you need to change this:

  class Author < ActiveRecord::Base
    has_many :posts
    has_many :taggings, :through => :posts
  end

  class Post < ActiveRecord::Base
    has_one :tagging
    has_many :taggings
  end

  class Tagging < ActiveRecord::Base
  end

To this:

  class Author < ActiveRecord::Base
    has_many :posts
    has_many :taggings, :through => :posts, :source => :tagging
  end

  class Post < ActiveRecord::Base
    has_one :tagging
    has_many :taggings
  end

  class Tagging < ActiveRecord::Base
  end

When using symbol keys, ActiveRecord will now translate aliased attribute names to the actual column name used in the database:

With the model

  class Topic
    alias_attribute :heading, :title
  end

The call

  Topic.where(heading: 'The First Topic')

should yield the same result as

  Topic.where(title: 'The First Topic')

This also applies to ActiveRecord::Relation::Calculations calls such as `Model.sum(:aliased)` and `Model.pluck(:aliased)`.

This will not work with SQL fragment strings like `Model.sum('DISTINCT aliased')`.

Github #7839

*Godfrey Chan*

Allows you to do BaseClass.new(:type => "SubClass") as well as
parent.children.build(:type => "SubClass") or parent.build_child
to initialize an STI subclass. Ensures that the class name is a
valid class and that it is in the ancestors of the super class
that the association is expecting.

All tests with a custom inheritance_column use the `Vegtable` model.
The field ruby_type on the Company models is no longer needed

It's not really a good idea to have this as a global config option. We
should allow people to specify the behaviour per association.

There will now be two new values:

* :dependent => :restrict_with_exception implements the current
  behaviour of :restrict. :restrict itself is deprecated in favour of
  :restrict_with_exception.
* :dependent => :restrict_with_error implements the new behaviour - it
  adds an error to the owner if there are dependent records present

See #4727 for the original discussion of this.

This reverts commit 3803fcce.

Conflicts:
	activerecord/CHANGELOG.md

It will be deprecated only in 4.0, and removed properly in 4.1.

Change CollectionProxy#method_missing to use scoped.public_send, to
avoid a problem described in issue #2508 when trying to use class
methods with names like "open", that clash with private kernel methods.
Also changed the dynamic matcher instantiator to send straight to
scoped, to avoid another roundtrip to method_missing.

See the CHANGELOG for details.

Fixes #950.

This is to avoid confusing newbies, and to be consistent with the fact
that other options like :foreign_key already allow a symbol or a string.