Removed template_root as a configuration option

Removed template root from actionmailer configuration options as it seems to have been pulled out completely in favor of explicit definition via template_path / template_name.
Fix #9360 regression in content_for
Fix deletion of empty directories:

1. When comparing the directory to delete against the top level
   cache_path, use File.realpath to make sure we aren't comparing two
   unequal strings that point to the same path. This occurs, for
   example, when cache_path has a trailing slash, which it does in the
   default Rails configuration. Since the input to
   delete_empty_directories never has a trailing slash, the comparison
   will never be true and the top level cache directory (and above) may
   be deleted. However…

2. File.delete raises EPERM when trying to delete a directory, so no
   directories have ever been deleted. Changing the code to Dir.delete
   fixes that.
Use less hyperbole in the language re: allowed parameters
Update CHANGELOGS
Add tests for #9441
Merge pull request #9444 from frodsan/add_test_for_977455cc

Add tests for #9441
Merge pull request #9442 from czarneckid/adjust-generator-language

Use less hyperbole in the language re: allowed parameters
Make ActionDispatch::Journey::Path::Pattern#new raise more meaningful exception message.
Merge pull request #9434 from zires/dev

Journey::Path::Pattern#new raise more meaningful exception message.
Move the CHANGELOG entry to the proper place

[ci skip]
Add routing guide doc on root with namespaces.

I read #9419 and realized I didn't know you could have namespaced
roots, checked around, and a few friends didn't either.  Figured
this makes it guide worthy.
Fix touching an invalid parent record for belongs_to

If the parent of a `belongs_to` record fails to be saved due to
validation errors, `touch` will be called on a new record, which causes
an exception (see https://github.com/rails/rails/pull/9320).

Example:

    class Owner < ActiveRecord::Base
      validates_presence_of :name
    end

    class Pet < ActiveRecord::Base
      belongs_to :owner, touch: true
    end

    pet = Pet.new(owner: Owner.new)

    # Before, this line would raise ActiveRecord::ActiveRecordError
    # "can not touch on a new record object"
    pet.save
Merge pull request #9443 from exviva/belongs_to_touch_new_record

Fix touching an invalid parent record for belongs_to
Merge pull request #9446 from bemurphy/enhance_root_route_guide

Add routing guide doc on root with namespaces. [ci skip]
We want i18n >= 0.6.2 but < 1.0
Merge pull request #9329 from chuckbjones/fix-cache-delete-rc

Fix deletion of empty directories
Move AS CHANGELOG entry up.

I merged b883706 but forgot to move the entry past beta1.
Fix default output for postgres network address types
Merge pull request #8010 from subwindow/postgres_inet_default_fix

Fix default output for postgres network address types