replace regexp global in #url_for
Fix file name in document [ci skip]

This file was renamed in c8a25386d.
Fixing the examples for button_to

The examples do not generate the output they intend to due to not explicitly declaring the hash separations. This causes it to be treated as one parameter instead of the intended two parameters.
Change Class#subclasses doc example
Add ActiveRecord.count documentation when used on group relations
Add documentation for ActiveRecord.select when use strings as arguments
Add example for ActiveRecord::Base.group using a string as argument
Add example for ActiveRecord::Base.joins using a string as argument
Validations guide: validates_with init clarification.

As discussed with @josevalim on Ruby Rogues Parley.
Clarify ActiveModel::Validator initialization in docs.

As discussed with @josevalim on Ruby Rogues Parley.
Fix CoffeeScript example

`a[data-color]` is not used in example html.
Fix supported ruby version for Rails 4
Fix typo.
[ci skip]
Detail Ruby 1.8 ships with TestUnit and Ruby 1.9 with MiniTest
Correct bullet content line wrapping

The `:prefix` bullet content was not properly wrapping,
dropping to the following line because the additional
content was not indented properly. With this change, it
will now display properly the way `:discard_type` does.
incorrect content of models/comment.rb after 'rails generate'
Revert "incorrect content of models/comment.rb after 'rails generate'"

This reverts commit 0f0803fda5df60319d8646bb4f3e71f2e596316a.

Reason: The content was correct since attr_accessible was removed from
rails master.
9253: Before writing a numeric attribute value, ActiveRecord does an implicit
conversion of boolean types (true => 1 and false => 0). If the numeric value
being assigned is a BigDecimal, then ActiveRecord compares a BigDecimal to
true and false. This is known to be very slow in Ruby 1.9.3.
Merge pull request #9254 from warnickr/9253_avoid_bigdecimal_performance_issue

Before writing a numeric attribute value, ActiveRecord does an implicit conversion of boolean types (true => 1 and false => 0). If the numeric value being assigned is a BigDecimal, then ActiveRecord compares a BigDecimal to true and false.

This is known to be very slow in Ruby 1.9.3 (see http://www.ruby-forum.com/topic/4409452 and https://bugs.ruby-lang.org/issues/7645#change-35188).

The Ruby core team has implemented a fix for this issue that will be included in Ruby 2, but they appear to have no intention of back-porting this fix to Ruby 1.9.3. In my case, the performance impact of this issue was enormous (200% - 300% performance hit) for some of the pages in my application.

See c75b5a88a82c79fdf95dfea4d72bf3c5a829930e applied to 3-2-stable branch for more reasoning and a benchmark.
Make valid_type? public