Abstract some common code from AssociationScope and JoinDependency::JoinAssociation into a JoinHelper module

Rename Reflection#through_reflection_chain and #through_options to Reflection#chain and Reflection#options as they now no longer relate solely to through associations.

Move the code which builds a scope for through associations into a generic AssociationScope class which is capable of building a scope for any association.

[#6550 state:committed]
Signed-off-by: NSantiago Pastorino <santiago@wyeworks.com>

Rails 3 cherry-picks as little as possible from Active Support. In particular
the framework requires the files where extensions are exactly defined, rather
than convenience entry points like float.rb and friends. Because of that, it
is better to define conditionally rather than require conditionally.

revises links to the API websites of individual components (no longer maintained), and rewrites the section about after and around filters in the controller guide

[#6529 state:committed]
Signed-off-by: NSantiago Pastorino <santiago@wyeworks.com>

This was conflicting with ActionView::Helpers::TextHelper#simple_format
from within email templates.

The root route example was the only using double quotes; switched it to single quotes for consistency

removing stubs. 1.9.3 implements Date.today in C so mocking the return value of Time.now does nothing

do not test explicit equality of predicate methods, they should be allowed to return truthy or falsey objects

Referencing a table via the ON condition in a join should force that table to be eager-loaded via a JOIN rather than via subsequent queries.

* 'master' of github.com:rails/rails: (44 commits)
  Fixed indentation in actionmailer base_test [#6538 state:committed]
  remove unused assigned variable
  removes merge conflicts
  removes Examples headers introduced in 9b96de6f
  Revert "Fixed identation in actionmailer base_test"
  Report the correct value of nil.id in the exception message as different ruby implementations may have different values, for example Rubinius returns 53 for nil.id.
  Improve testing of cookies in functional tests: - cookies can be set using string or symbol keys - cookies are preserved across calls to get, post, etc. - cookie names and values are escaped - cookies can be cleared using @request.cookies.clear
  more style changes
  Some style changes
  style changes
  Revert "style changes"
  Raise ArgumentError if route name is invalid [#6517 state:resolved]
  style changes
  Allow model to be inherited from Hash [#6487 state:resolved]
  styles applied for usage
  added failing test for fields_for with a record object that inherits from Hash
  Fixed identation in actionmailer base_test
  wrong SQL statement
  commas to set off expressions that interrupt sentence flow
  typo changes
  ...

Referencing a table via the ON condition in a join should force that table to be eager-loaded via a JOIN rather than via subsequent queries.

Merge branch 'active_model_unused_variable' of https://github.com/pacoguzman/rails into pacoguzman-active_model_unused_variable

Refactor ThroughAssociation#join_to to be much smaller, and independent of construct_owner_conditions.

Signed-off-by: NXavier Noria <fxn@hashref.com>