The [current documentation of form_for](http://api.rubyonrails.org/classes/ActionView/Helpers/FormHelper.html#method-i-form_for) is incomplete:

> The rightmost argument to form_for is an optional hash of options -
>   :url - The URL the form is to be submitted to. This may be represented in the same way as values passed to url_for or link_to. So for example you may use a named route directly. When the model is represented by a string or symbol, as in the example above, if the :url option is not specified, by default the form will be sent back to the current url (We will describe below an alternative resource-oriented usage of form_for in which the URL does not need to be specified explicitly).
>   :namespace - A namespace for your form to ensure uniqueness of id attributes on form elements. The namespace attribute will be prefixed with underscore on the generated HTML id.
>   :html - Optional HTML attributes for the form tag.

This commit completes the documentation by specifying that:

* `:authenticity_token` is also a valid option (as [documented here](https://github.com/rails/rails/blob/b0f44c9ff0be84ebc42760029adeeb9dd954655f/actionview/lib/action_view/helpers/form_helper.rb#L396))
* `:method` is also a valid option (as [tested here](https://github.com/rails/rails/blob/b0f44c9ff0be84ebc42760029adeeb9dd954655f/actionview/test/template/form_helper_test.rb#L1819))
* `:remote` is also a valid option (as [tested here](https://github.com/rails/rails/blob/b0f44c9ff0be84ebc42760029adeeb9dd954655f/actionview/test/template/form_helper_test.rb#L1850))

[ci skip]

[CI SKIP] Improvements to Active Job guide.

PERF: avoid string allocations

This makes the following changes:
  * warn if `:null` is not passed to `add_timestamps`
  * `timestamps` method docs link to `add_timestamps` docs
  * explain where additional options go
  * adjust examples to include `null: false` (to prevent deprecation warnings)

Now ActionView accepts <%= foo(){ %> and <%= foo()do %> ⛳

Allow class_name option in habtm to be consistent with other association...

It doesn't make sense for the subclass to implement this method, and not
have it on the parent. We can also DRY up the implementation of
`#lookup` to be defined in terms of fetch, which will give us a single
point of entry

Remove bullet point to unwritten/unreferenced section

This reverts commit da99a2a2.

Support symbol foreign key to delete

Add space in :start_year description for date_select

We added a comparison to "id", and call to `self.class.primary_key` a
*lot*. We also have performance hits from `&block` all over the place.
We skip the check in a new method, in order to avoid breaking the
behavior of `read_attribute`

We don't have the check the range when the value is coming from the DB,
so override type_cast_from_database to short-circuit the extra work.
The difference is huge but the absolute gain is quite small. That being
said this is a hotspot and it showed up on the radar when benchmarking
discourse.

This reverts commit f93df528, reversing
changes made to a455e3f4.

Conflicts:
	actionpack/lib/action_controller/test_case.rb
	actionview/lib/action_view/test_case.rb

This appears to be a performance hotspot, see #17655.

Performance improvement, as well as improved code clarity

Ruby on Rails 3.0 Release Notes: fix broken link

fixed minor typos in RELEASE doc [ci skip]

PERF: stop allocating the string "id" over and over

This reverts commit 6f7910ae and 52c70d49.

Query params are type cased through the same method, so this approach doesn't work.

See comment on 6f7910ae

We don't have the check the range when the value is coming from the DB, so
override type_cast_from_database to short-circuit the extra work.

type_cast_from_database (small)  3437507.5 (±29.2%) i/s -   14223135 in   4.996973s
type_cast_from_database (large)  3158588.7 (±28.3%) i/s -   13265628 in   4.992121s
type_cast (small)                 481984.8 (±14.2%) i/s -    2352012 in   5.005694s
type_cast (large)                 477331.8 (±14.2%) i/s -    2332824 in   5.012365s

Comparison:
type_cast_from_database (small):  3437507.5 i/s
type_cast_from_database (large):  3158588.7 i/s - 1.09x slower
type_cast (small):                 481984.8 i/s - 7.13x slower
type_cast (large):                 477331.8 i/s - 7.20x slower

The difference is huge but the absolute gain is quite small. That being said
this is a hotspot and it showed up on the radar when benchmarking discourse.

Oh hey, we got to remove some code because of that!

Arel handles this for us automatically. Updated tests, as BindParam is
no longer a subclass of SqlLiteral. We should remove the second argument
to substitute_at entirely, as it's no longer used

If something causes the teardown block to not get run (errors,
interrupting test runs), we have to manually delete them, which is a
pain.