Builder's #tag! takes either String or Symbol as the first parameter

As of Rails 4.0 `remove_column` is no longer an alias for `remove_columns`.
The type is actually valid and used when issuing a rollback (new `change` method).

This reverts commit 9c9d4948.

[ci skip] Fix curl response output and use strong parameters in update action

Remove the unused, undocumented SQLite3Adapter#supports_count_distinct?

    
This has returned true since 3cc9b5f1, and is not used internally.

Drop some comments that document the implementation rather than the interface.

Allow Pathnames to be added to eager load paths

Include URL helpers in TestController in bug report templates [ci skip]

[ci skip]

Fixes #12848.

updated documentation for Integer [ci skip]

Make static error pages responsive

methods and outputs indented [ci skip]

Fixes #11079, prevent the counter cache from being decremented twice when destroying a record on a has_many :through association

when destroying a record on a has_many :through association.
:destroy method has own counter_cache callbacks.

Update security.md [ci skip]

Unify boolean quoting for Mysql- and Mysql2Adapter.

Fixed typo in migrations guide [ci skip]

Product model name was pluralized in example in migrations guide.
[ci skip]

addresses "ArgumentError: comparison of VerySpecialComment with SpecialComment failed" in ActiveRecord::DelegationRelationTest#test_#sort!_delegation_is_deprecated

Without this, some tests here were not actually testing anything.

Fixes problem with replacing has_one association record with itself

[ci skip]

autoload ChangeColumnDefinition (Fixes #12835)

Fix missing line and shadow on static error pages [ci skip]

Speed up Array#split when block is passed

Ruby 2.0.0p247
Rehearsal ---------------------------------------
old  10.670000   0.150000  10.820000 ( 10.822651)
new   8.520000   0.050000   8.570000 (  8.571825)
----------------------------- total: 19.390000sec

          user     system      total        real
old  10.620000   0.170000  10.790000 ( 10.790409)
new   8.570000   0.110000   8.680000 (  8.686051)

Array#in_groups: documentation updated [ci skip]