[Jonas Baumann & Yves Senn]

The submitted params from a select with `multiple: true` look as follows:

```
{post: {category: [""]}}

{post: {category: ["", "Category 1", "Category 2"]}}
```

This is a follow up to #1552.

Remove need for macro instance var

Remove "profile and benchmark" line from command line guide

The profiling and benchmarking commands are no longer built into Rails.

Same as we did for collection, removed the `@macro` instance var
and it is now set in each association. Unfortunately it can't be
left undefined in AssociationReflection so it has to be set there.
For now I am setting it to NotImplementedError since there is no
default macro and it changes based on the reflection type.

Fix broken list formatting in API docs [ci skip]

this way we only have to test for whether it is a rails app once.

Use an is_a check to ensure it's a Railsish app so we can avoid
respond_to calls everywhere.

Hopefully `object.class` always returns something that is_a?(Class), so
the previous logic didn't really make sense.

Remove unused 1:1 association :remote option

This option is unused, left over from pre-1.0 Rails to internally distinguish the location of the foreign key.

Revert "Rename to test_mysql_strict_mode_disabled_dont_override_global_sql_mode"

Fix typos in string_ext_test.rb

The performance is almost the same with both implementations but this is
clear.

Before this patch:

Calculating -------------------------------------
  small erb template      1452 i/100ms
-------------------------------------------------
  small erb template    17462.1 (±13.3%) i/s -      85668 in   5.031395s
.Calculating -------------------------------------
small erb template with 1 partial
                           887 i/100ms
-------------------------------------------------
small erb template with 1 partial
                         8899.6 (±18.8%) i/s -      42576 in   5.009453s
.Calculating -------------------------------------
small erb template with 2 partials
                           666 i/100ms
-------------------------------------------------
small erb template with 2 partials
                         6821.5 (±8.8%) i/s -      33966 in   5.020791s

After the patch:

Calculating -------------------------------------
  small erb template      1479 i/100ms
-------------------------------------------------
  small erb template    15956.6 (±7.6%) i/s -      79866 in   5.036001s
.Calculating -------------------------------------
small erb template with 1 partial
                           841 i/100ms
-------------------------------------------------
small erb template with 1 partial
                         9242.2 (±6.9%) i/s -      46255 in   5.029497s
.Calculating -------------------------------------
small erb template with 2 partials
                           615 i/100ms
-------------------------------------------------
small erb template with 2 partials
                         6524.7 (±6.8%) i/s -      32595 in   5.020456s

You can find the benchmark code at
https://gist.github.com/rafaelfranca/dee31120cfdb1ddc3b56

remove Set.new from DetailsKey::get, impacts rendering overhead

Word truncation

If we extract the options from the user facing method call ASAP, then we
can simplify internal logic.

Treat invalid uuid as nil

Conflicts:
	activerecord/CHANGELOG.md

Implement required #encode_with

people may be passing filenames to the constructor that are not utf-8,
but they will assome that calling `original_filename` returns utf-8
(because that's what it used to do).

Fixed a regression introduced in 84cf156e

Squash and merge #7698 doing some improvements to the original
implementation.

Closes #7698.

This class is only used on the PartialRenderer.

The iteration object is available as the local variable
"template_name_iteration" when rendering partials with collections.

It gives access to the +size+ of the collection beeing iterated over,
the current +index+ and two convinicence methods +first?+ and +last?+

"template_name_counter" variable is kept but is deprecated.

[Joel Junström + Lucas Uyezu]

These fixtures are not used in actionpack tests.

This reverts commit babc24c1.

Conflicts:

	activerecord/test/cases/adapters/mysql/connection_test.rb
	activerecord/test/cases/adapters/mysql2/connection_test.rb