Revert "`remove_column` does not take a type argument. [ci skip]. Closes #12864"

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 6a5e3647a8bfdca7ece7db30508a8b5db9709426.
Merge pull request #12870 from sauliusg/atom-feed-doc-fix

Fix syntax error in atom_feed example [ci skip]
Merge pull request #12845 from amatsuda/should_ar_depend_on_rails

Refer to Rails.env from AR only when Rails is defined
Conflicts:
	activerecord/lib/active_record/migration.rb
document id prefixed String usage of `.find`. refs #12891 [ci skip]
The option is called encode_big_decimal_as_string [ci skip]
Merge pull request #12906 from chancancode/use_standard_json_big_decimal_format-4-0-stable

(Doc fix) Backport ActiveSupport.encode_big_decimal_as_string doc fix to 4-0-stable [ci skip]
Merge pull request #12904 from sbagdat/patch-1

Change Relation#all to Relation#load [ci skip]
Merge pull request #12703 from makimoto/actionsupport-error-set_backtrace

Use set_backtrace instead of @backtrace in ActionView error
Conflicts:
	actionview/CHANGELOG.md
Merge pull request #12916 from petervandenabeele/typo_4_0_release_notes

[ci skip] typo in ArgumentError in 4_0_release_notes.md
Merge pull request #12918 from versioncontrol/rails-12866

Checks to see if the record contains the foreign_key to set the inverse automatically

Conflicts:
	activerecord/CHANGELOG.md

Conflicts:
	activerecord/CHANGELOG.md
rails new --edge should generate a edge version in the 4.0 family
Merge pull request #12970 from prathamesh-sonpatki/issue12885

Add positional information to eval call so that this information will be used in printing correct location where the exception occurred.

Closes #12885.
Use `SchemaStatements#initialize_schema_migrations_table` instead of `ActiveRecord::SchemaMigration.create_table`.
Merge pull request #12975 from sbagdat/fix-for-rake-routes

Fix for routes task
Conflicts:
	actionpack/CHANGELOG.md
	railties/test/application/rake_test.rb
Merge pull request #12996 from shreve/patch-2

Added a missing close parenthesis to i18n.md [ci skip]
Merge pull request #13012 from harrigan/master

Helper should be a module in Rails guides [ci skip]
sync example and documentation for strong_parameters hash whitelisting.

[ci skip]

This is a follow up to #12609 and integrates #12158.

Thanks @aspiers.
Closes #12158.

Conflicts:
	guides/source/action_controller_overview.md
Remove single trailing ')' bracket
Merge pull request #13057 from bricejlin/patch-1

Remove single trailing ')' bracket [ci skip]
Fix bug when validating the uniqueness of an aliased attribute.