Merge pull request #12365 from jbaudanza/reorder

Move Rack::Cache after ActionDispatch::Static in the middleware stack
`ActionView::MissingTemplate` for partials includes underscore.

Missing partial folder/_partial instead of folder/partial.

Closes #13002.
Typo and grammatical fixes [ci skip]
Merge pull request #11466 from jetthoughts/updated_tesing_guides

Fix `rake test` description in the guides [ci skip]
Merge pull request #13117 from akshay-vishnoi/typo

Typo and grammatical fixes [ci skip]
`mail()` without arguments is a getter for the current mail.

This behavior is documented in our guides (http://edgeguides.rubyonrails.org/action_mailer_basics.html#action-mailer-callbacks)
but was broken in the past. This commit short curcuits
the `mail` method if:

  1. mail() was previously called
  2. no headers are passed
  3. no block is passed

Closes #13090.

/cc @pixeltrix
added missing require

we’re using .delegate and should require it.
Merge pull request #13134 from rubiii/patch-1

added missing require to active_support/tagged_logging
activemodel isn't a runtime dependency for actionview
Make the tests break again

We need to fix this test
Unify cattr and mattr accessors declarations
Make the release notes consistent [ci skip]

Conflicts:
	guides/source/4_1_release_notes.md
:scissors:

[ci skip]
Use alphabetic order

[ci skip]
Add documentation about the Action Dispatch salt configuration

[ci skip]
Wrap 80 columns [ci skip]
Merge pull request #11197 from gsamokovarov/unify-mattr-cattr

Unify cattr and mattr accessors declarations
Make ActionView::Tags loading tread safe
Remove deprecated cattr_* requires
Add number and range field to form helpers article

Also wrap surrounding text to 80 chars.

[ci skip] Closes #13132