Render arbitrary templates outside of controller actions

This functionality has been extracted to the responders gem.

doesn't contain `#`

Commit 20fece14 introduced the `_status_code` method to fix calls to
`head :ok`. This method has been added on both ActionController::Metal
and ActionDispatch::Response.

As for the latter, this method is just equivalent to the `response_code`
one so commit aefec3c6 removed it from the `Reponse` object so call to
the `_status_code` method on an ActionController::Base instance would be
handled by the `Metal` class (which `Base` inherits from) but the status
code is not updated according to the response at this level.

The fix is to actually rely on `response_code` for ActionController::Base
instances but this method doesn't exist for bare Metal controllers so we
need to define it.

- The single space response was added due to a bug in safari
  in https://github.com/rails/rails/commit/cb0f8fda9652c4d24d04693bdb82cecd3b067e5c
  and
  https://github.com/rails/rails/commit/807df4fcf021fc4d15972aa1c17ba7398d43ab0d.
- This was removed from the `render nothing: true` in
  https://github.com/rails/rails/pull/14883.
- Removing it from response of :head also. As :head is more obvious
  alternative to call `render nothing:
  true`(http://guides.rubyonrails.org/layouts_and_rendering.html#using-head-to-build-header-only-responses),
  removing it from head method also.
- Closes #18253.

There is no need to subtract one from the path_params size when there is
no format parameter because it is not present in the path_params array.

Fixes #17819.

See:
* https://github.com/rails/rails/pull/14903
* https://github.com/roidrage/lograge/issues/37

Some code by mxrguspxrt from #14903.

We will support only Ruby >= 2.1.

But right now we don't accept pull requests with syntax changes to drop
support to Ruby 1.9.

Fixes https://github.com/rails/rails/issues/16958

[Byron Bischoff & Melanie Gilman]

In cases where this option is set to `true`, the option is redundant and can
be safely removed; otherwise, the corresponding `*_url` helper should be
used instead.

Fixes #17294.

See also #17363.

[Dan Olson, Godfrey Chan]

The scanner in Journey fails to recognize routes that use literals
from the sub-delims section of RFC 3986.

This commit enhance the compatibility of Journey with the RFC by
adding support of authorized delimiters to the scanner.

Fix #17212

[ci skip]

Fixes #17057

IPAddr::InvalidAddressError does not exist in Ruby 1.9.3
and fails for JRuby in 1.9 mode.

As IPAddr::InvalidAddressError is a subclass of ArgumentError
(via IPAddr::Error) just rescuing ArgumentError is fine.

https://github.com/rails/rails/commit/402c2af55053c2f29319091ad21fd6fa6b90ee89
introduced a regression that caused any constraints added to redirect routes
to be ignored.

Fixes #16605