fix HashWithIndifferentAccess#to_hash behaviour

* polymorphic: (41 commits)
  fix shadowed variable warnings
  polymorphic around callbacks
  polymorphic after filter
  rename terminal to halting, try to keep naming consistent
  push the before filter lambdas to factory methods
  polymorphic before callbacks
  use a singleton end node
  Revert "we never pass blocks, so remove this"
  if there is nothing to compile, then do not bother compiling
  Arrays are no longer supported
  we never pass blocks, so remove this
  raise an argument error if the filter arity is greater than 1
  pass the actual filter, not a string
  do not keep a reference to the chain in the callback objects
  fix deprecation test
  push merge code to the callback itself
  dup the callback and set the chain
  remove klass because it is not used
  rename instance variables
  push duplicates? logic to the instance
  ...

Removed Class Eval and used define_method instead for the SafeBuffer

* master:
  private callback methods should work
  Update mail to minimum version 2.5.4

This reverts commit 9caf0cf9.

* master:
  adding more callback type coverage

* master:
  extract getting an setting callbacks to methods
  call extracted method from callback manipulation methods
  extract callback param munging
  no reason to make these defaulted, we always pass values in

Conflicts:
	activesupport/lib/active_support/callbacks.rb

* master: (61 commits)
  add tests for reset_calbacks
  Fixing build broken by this change
  Extract variable out of loop
  Updated comment to Rails 4
  Fixes NoMethodError: `alias_method_chain` when requiring just active_support/core_ext
  better error message when app name is not passed in `rails new`
  Code cleanup for ActionDispatch::Flash#call
  Fix typo: require -> requires
  Add CHANGELOG entry for #10576
  Merge pull request #10556 from Empact/deprecate-schema-statements-distinct
  Some editorial changes on the documentation.
  respond_to -> respond to in a message from AM::Lint
  specify that dom_(id|class) are deprecated in controllers, views are fine
  copy edits [ci skip]
  Fix class and method name typos
  Replace multi_json with json
  ruby -> Ruby
  Adding documentation to the automatic inverse_of finder.
  Improve CHANGELOG entry [ci kip]
  Call assume_migrated_upto_version on connection
  ...

Conflicts:
	activesupport/lib/active_support/callbacks.rb

Fixing build broken by this change

c43ca06c

Extract variable out of loop

Fixes NoMethodError: `alias_method_chain` when requiring just active_support/core_ext

Updated comment to Rails 4