Added method `#eql?` to `ActiveSupport::Duration`, in addition to `#==`.

Currently, the following returns `false`, contrary to expectation:

    1.minute.eql?(1.minute)

Adding method `#eql?` will make this behave like expected. Method `#eql?` is
just a bit stricter than `#==`, as it checks whether the argument is also a
uration. Their parts may be different though.

    1.minute.eql?(60.seconds)  # => true
    1.minute.eql?(60)          # => false
SQLite3Adapter now checks for views in table_exists? fixes: 14041
Update RecordNotFound exception cases to include a message with the
Model that the Record was not found in.
Updating Associations::Preloader docs

Much of the previous documentation introduced features new in 2011. This
commit refreshes it to provide clearer code examples and spends more
time describing the normal case (preloaded associations) and less time
describing the fallback.

[ci skip]
Roll back open transactions when the running thread is killed.
disable migrations logging while running test cases for AR schema tests
Fix query with nested array in Active Record

`User.where(id: [[1,2],3])` was equal to `User.where(id:[1, 2, 3])`
in Rails 4.1.x but because of some refactoring in Arel this stopped
working in 4.2.0. This fixes it in Rails.

[Dan Olson & Cristian Bica]
Convert string concatenations to substitutions
Prefer "if any?" to "unless empty?"

* Consistent whitespace
* Remove unnecessary parentheses
Fix warnings for undefined local variable

* Add private method primary_key_for, which more clearly shows that the
expected return value is nil when a primary key is not found.
Merge pull request #16830 from teeparham/schema_dumper

Cleanup SchemaDumper
Schema dumper: all connection adapters implement #primary_key, so rely on it exclusively
Removing unused fake models
Merge pull request #16834 from tchandy/removing_unused_fake_models

Removing unused fake models
Merge pull request #16825 from cristianbica/fix-ar-nested-arrays

Fix query with nested array in Active Record
Merge pull request #16827 from kuldeepaggarwal/f-disable-migration-logging

disable migrations logging while running test cases for AR schema tests
Default to sorting user's test cases for now

Goals:

1. Default to :random for newly generated applications
2. Default to :sorted for existing applications with a warning
3. Only show the warning once
4. Only show the warning if the app actually uses AS::TestCase

Fixes #16769
Do not memoize document_root_element in view tests

Memoizing will not make possible to assert the output of the view if it
is changed after the first assert_select call

Related with plataformatec/simple_form#1130 and rails/rails-dom-testing#15
Add docs for web-console to 4.2 Upgrade Guide [ci skip]
Merge pull request #16845 from todd/upgrade_guide_console_docs

Add docs for web-console to 4.2 Upgrade Guide