Also dup `column_types` in AR::Result `initialize_copy`
Refer to Rails.env only when Rails is defined
Move `SchemaCreation` to its own file instead of `AbstractAdapter`.
add #no_touching on ActiveRecord models
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 9c9d4948e428a226a19aa92c17fa6ac5833c2fb8.
Ensure that a column added in a test is being removed after all
Fix syntax error in atom_feed example [ci skip]

Builder's #tag! takes either String or Symbol as the first parameter
Merge pull request #12870 from sauliusg/atom-feed-doc-fix

Fix syntax error in atom_feed example [ci skip]
move Relation#merge tests into separate file.
tests for merging Relations of different classes.
fix weird Emacs auto indentation. [ci skip]
Merge pull request #12772 from dmathieu/no_touching

Add No Touching
Make it clear that require 'active_support' is required [ci-skip]
Merge pull request #12874 from chancancode/better_as_loading_guides

Make it clear that require 'active_support' is required [ci-skip]
Use rescue with a splat rather and catching all and filtering
Merge pull request #12882 from charliesome/use-rescue-splat-in-suppress

Use rescue with a splat rather and catching all exceptions and manually filtering in Kernel#suppress
Updated guides link for 3.2.x to latest stable version 3.2.15 [skip-ci]
Get rid of unused  variable
Merge pull request #12883 from Amit-Thawait/master

Updated guides link for 3.2.x to latest stable version 3.2.15 [ci skip]
Merge pull request #12845 from amatsuda/should_ar_depend_on_rails

Refer to Rails.env from AR only when Rails is defined