Fixes #18905. `#touch` now takes time as an option. Setting the option
saves the record with the updated_at/on attributes set to the current time
or the time specified. Updated tests and documentation accordingly.

Replace deprecated readonly option with scope blocks in docs and guide

Prefer `drop_table if_exists: true` over raw SQL

Lowercase raw SQL has been replaced by 07b659ca already. This commit
replaces everything else of raw SQL.

Not sure how this one slipped, maybe deleted by accident while editing or
something. Anyway, fixed.

/cc @yahonda

This makes it easier for third party adapters to run our tests,
even if that database does not support IF EXISTS.

fix typo in guide - missing word

Add guide for Action Mailer Previews

This helper no longer makes sense as a separate method. Instead I'll
just have `deserialize` call `cast` by default. This led to a random
infinite loop in the `JSON` pg type, when it called `super` from
`deserialize`. Not really a great way to fix that other than not calling
super, or continuing to have the separate method, which makes the public
API differ from what we say it is.

These files get modified whenever someone uses a tool like `sed`. Let's
just get this over with in one commit so it'd not adding diff noise to
something else.

This reverts commit 1502caef.

The test suite for the mysql adapter broke when this commit was used
with MySQL 5.6.

Conflicts:
	activerecord/CHANGELOG.md

Deprecated passing of `start` value to `find_in_batches` and `find_each`

Deprecated passing of `start` value to `find_in_batches` and `find_each` in favour of `begin_at` value.

* "rm docs for dependency_loading and disable_dependency_loading config"

It was added back in a71350ca by @tenderlove

See also #13142

This reverts commit a8bf1297.

removes documentation that is no longer relevant

removes docs for dependency_loading config option and disable_dependency_loading initializer because it was removed by commit a8bf1297

Remove unused Rails::Server#log_path

Adding 'Search Engines Indexing' Section [ci skip]

Add web console in debugging rails applications guide [ci skip]  

Correct pluralization error

Improving remote forms guides [ci skip]

With refactors to Rails::Sever from v3 to v4, this method is no longer used and is untested.

Previous usage: https://github.com/rails/rails/blob/3-2-stable/railties/lib/rails/commands/server.rb#L79
Currently set from: https://github.com/rails/rails/blob/7b75551a1a4539876f878f37a2439cd02f89d961/railties/lib/rails/application/configuration.rb#L69

Allow to pass a string value to size option in `image_tag` and `video_tag`

This makes the behavior more consistent with `width` or `height` options

Add `foreign_key_exists?` method.

Add Gemfile.lock to plugin's gitignore template

We do this in the adapter classes specifically, so the types aren't
registered if we don't use that adapter. Constants under the PostgreSQL
namespace for example are never loaded if we're using mysql.