The `subclass_from_attrs` method is called even if the column specified by
the `inheritance_column` setting doesn't exist. This prevents setting associations
via the attributes hash if the association name clashes with the value of the setting,
typically `:type`. This worked previously in Rails 3.2.

Example:

    class Conversation < ActiveRecord::Base
      enum status: [ :active, :archived ]
    end

Before:

    Conversation::STATUS # => { "active" => 0, "archived" => 1 }

After:

    Conversation.statuses # => { "active" => 0, "archived" => 1 }

Single quotes for controller generated routes. This is more consistent with all other Rails generated code.

Fix fields_for documentation with index option [ci skip]

- fields_for documentation with index option was wrong.
- It does not work with passing model as it is.
- Changed the example by passing id of the address object.
- Fixes #13125.

[ci skip] Grammar correction

Set NameError#name

[ci skip] Added alias to CSRF

Write routes in route.rb with single quotes

    get 'welcome/index'

instead of

    get "welcome/index"

It's not public API, but is not private scoped.

"serie" => "series"

More to come.

Favor canonical environment variables for secrets

Prefixing an environment variable with `RAILS_` should be used when there is otherwise a conflict, such as `RAILS_ENV` or if it is being used for a very Rails specific value.

If we remove the prefix of `RAILS_` in the case of `RAILS_SECRET_KEY_BASE` then we can push for a pseudo standard among other frameworks that will accept a common environment key `SECRET_KEY_BASE` to keep your app secure. This is beneficial for containerized deployments such as docker, Heroku, etc. So that the container need to know one less thing about your app (it can just set it no-matter what language or framework you are using). 

This change also allows the defaults to be consistent with the way the secret key is accessed so `secrets.secret_key_base` is aliased to `SECRET_KEY_BASE` instead of `RAILS_SECRET_KEY_BASE`.

removed extra comma [ci skip]

This prevents Rails from assigning meaningless log levels to third
party loggers like log4r. If `Rails.logger` is not `kind_of?(::Logger)`
we simply assign the `config.log_level` as is.

This bug was introduced by #11665.

Updated Changelog to reflect removal of :dependent => :restrict

Based on https://github.com/rails/rails/issues/2502, the option has
been removed.

[JRuby] Fix incorrect RUBY_ENGINE value 

This Adds helpers(jruby_skip & rbx_skip). In Future, Plan is to use
these helpers instead of calls directly to
RUBY_ENGINE/RbConfig/JRUBY_VERSION

This has no effect on the API docs. The main API page is taken from:
    railties/RDOC_MAIN.rdoc

Skip Spring App Generator tests on JRuby

Clarify behavior of json_escape [ci skip]

use enum labels as form values. Achieved by `_before_type_cast`.

Spring makes extensive use of Process.fork, so won't be able to provide
JRuby Support, hence skip these tests on JRuby.

Kudos to @zzak for taking over SDoc and make it work with RDoc 4.