I think we should deprecate this behavior and just error if you tell us
to do a case insensitive comparison for types which are not case
sensitive. Partially reverts 35592307

Fixes #18195

With rails/coffee-rails#61 (and #17241), the `.coffee` extension is
favoured over `.js.coffee`. Respectively, with rails/sass-rails#271
`.scss` and `.sass` are favoured over `.css.scss` and `.css.sass`.

Let's update the documentation to reflect that.

[ci skip]

Dump the default `nil` for PostgreSQL UUID primary key.

Fixed warning `possible reference to past scope` from railties

Fixed AR warning on ruby 2.2

Targeting 2.2

Remove unnecessary double space

Remove ActionController::ModelNaming

Check for Rails.env instead of Rails

`Rails` constant is added by rails-html-sanitizer leading to bugs in
non-Rails apps using ActiveRecord and ActionMailer

The methods in these modules are not used anywhere. They used to be
invoked in polymorphic_routes.rb but their usage was removed in e8210450.

What is your opinion about removing these methods?

They do belong to the public API, but in reality their code has already been duplicated to ActionView::ModelNaming, since they are used by methods like `dom_id` and `dom_class` to associated records with DOM elements (in
ActionView).

Please tell me if you think that removing this module is a good idea and,
in that case, if the PR is okay as it is, or you'd rather start by showing
a deprecation message, and remove the module in Rails 5.1.

List the Active Support Instrumentation guide in the index (as WIP)

Fix grammar in Caching with Rails docs

Fix bug in ActionMailer guide.

When setting a mailer's default from address, you have to pass a hash
with a `:from` key; you can't pass just an email address.

Add support for Reply-To field in mail_to helper

Removed unused parameter to cookie serialize method

Describe full behaviour of Active Record's attribute query methods

Clarify that query methods have a custom definition of whether a numeric value is present. [ci skip]

The way Active Record query methods handle numeric values is a special case, and is not part of Rails's standard definition of present. This update attempts to make this more clear in the docs, so that people don't expect Object#present? to return false if used on a number that is zero.

References #18148.

Remove unneeded special case to calculate size for has_many :through

All cases are properly handled in CollectionAssociation
for all subclasses of this association

[ci skip]

We were ignoring the `default_value?` escape clause in the serialized
type, which caused the default value to always be treated as changed.

Fixes #18169