* Avoid double hash lookups in AR::Reflection when reflecting associations/aggregations
* Minor cleanups: use elsif, do..end, if..else instead of unless..else
* Simplify DynamicMatchers#respond_to?
* Use "where" instead of scoped with conditions hash
* Extract `scoped_by` method pattern regexp to constant
* Extract noisy class_eval from method_missing in dynamic matchers
* Extract readonly check, avoid calling column#to_s twice in persistence
* Refactor predicate builder, remove some variables

Add ActiveModel::Model, a mixin to make plain Ruby objects work with AP out of box

Closes #5245

It fails if routes from to railties are called in one context,
for example: blog.posts_path and main_app.users_path

don't pass unnecessary argument

Optimize routes generation in simple cases.

If you pass to the route helper the same amount of arguments
as the required segments, route generation will be optimized
as a string interpolation. After this commit, `post_path(post)`
is about 6.5 times faster, `post_url(post)` is about 5 times.

Stop SafeBuffer#clone_empty from issuing warnings

Logic in clone_empty method was dealing with old @dirty variable, which
has changed by @html_safe in this commit:
https://github.com/rails/rails/commit/139963c99a955520db6373343662e55f4d16dcd1

This was issuing a "not initialized variable" warning - related to:
https://github.com/rails/rails/pull/5237

The logic applied by this method is already handled by the [] override,
so there is no need to reset the variable here.

Allow empty fieldsets  to be created without a block.

Commit 3dbedd28 added NOT NULL constraints both to table
creation and modification. For creation the new default
makes sense, but the generic situation for changing a
table is that there exist records. Those records have
no creation or modification timestamps, and in the
general case you don't even know them, so when updating
a table these constraints are not going to work. See
a bug report for this use case in #3334.

Add release dates to documentation

Set "March 1, 2012" as the release date for 3.2.2, 3.1.4, 3.0.12

* master-security:
  Ensure [] respects the status of the buffer.
  delete vulnerable AS::SafeBuffer#[]
  use AS::SafeBuffer#clone_empty for flushing the output_buffer
  add AS::SafeBuffer#clone_empty
  fix output safety issue with select options

Conflicts:
	actionpack/lib/action_view/helpers/tags/base.rb

Fix layout lookup for anonymous controller

Fix for #2781

We have an empty api doc page otherwise :)

Fix warning: assigned but unused variable

remove unnecessary memcache require in ActionDispatch CacheStore

update_only documentation for accepts_nested_attributes_for

Inject in constantize

force datetime attributes to be changed, fix GH #3965