The api for filters with classes change and the guides weren't updated.
Now the class must respond for methods with the same name as the filter,
so the `before_action` calls a `before` method, and so on.

The method `#filter` has been deprecated in 4.0.0 and has been removed
in 4.1.0: #7560

MessageEncryptor has :serializer option, where any serializer object can
be passed. This commit make it possible to set this serializer from configuration
level.

There are predefined serializers (:marshal_serializer, :json_serialzier)
and custom serializer can be passed as String, Symbol (camelized and
constantized in ActionDispatch::Session namepspace) or serializer object.

Default :json_serializer was also added to generators to provide secure
defalt.

Both Time#xmlschema and DateTime#xmlschema can accept nil values for the
fraction_digits parameter. This commit makes this so for TimeWithZone
values as well.

The subsecond fraction digits had been hardcoded to 3. This forced all
timestamps to include the subsecond digits with no way to customize the
value. While the subsecond format is part of the ISO8601 spec, it is not
adhered to by all parsers (notably mobile clients). This adds the
ability to customize the number of digits used, optionally setting them
to 0 in order to eliminate the subsecond fraction entirely:

ActiveSupport::JSON::Encoding.subsecond_fraction_digits = 0

Currently if a time is changed during DST overlap in the autumn then the
method `period_for_local` will return the DST period. However if the
original time is not DST then this can be surprising and is not what is
generally wanted. This commit changes that behavior to maintain the current
period if it's in the list of periods returned by `periods_for_local`.

It is possible to alter the behavior of `period_for_local` by specifying a
second argument but since we may be change from another time that could be
either DST or not then this would give inconsistent results.

Fixes #12163.

The file is config/secrets.yml, not config/initializers/secrets.yml.

sup haters

This change breaks tests in activesupport/test/core_ext/module_test.rb:

* test_delegation_exception_backtrace
* test_delegation_exception_backtrace_with_allow_nil

This reverts commit 0167765e.

any line number maths

This Adds helpers(jruby_skip & rbx_skip). In Future, Plan is to use
these helpers instead of calls directly to
RUBY_ENGINE/RbConfig/JRUBY_VERSION

- Fixes #13667

The behavior of json_escape was fixed in 2f1c5789, but the doc
changes and example in that commit incorrectly indicated that the
return value would be html-safe. Since quotation marks are
preserved, the raw value is not safe to use in other contexts
(specifically HTML attributes).

Check `respond_to` before delegation due to: https://github.com/ruby/ruby/commit/d781caaf313b8649948c107bba277e5ad7307314

  * Adding Hash#compact and Hash#compact! methods
  * Using Ruby 1.9 syntax on documentation
  * Updating guides for `Hash#compact` and `Hash#compact!` methods
  * Updating CHANGELOG for ActiveSupport
  * Removing unecessary protected method and lambda for `Hash#compact` implementations
  * Performing `Hash#compact` implementation - https://gist.github.com/tinogomes/8332883
  * fixing order position
  * Fixing typo

fixes #13547

The body may use the local cache during rendering.  `call`ing the app
doesn't mean that rendering is finished, so we need to wait until
`close` is called on the body.

This reverts commit 2ef1fb2c.

As described in PR #13627 this commit broke functionality when passing
a negative Fixnum to the `String#to` method:

```ruby
assert_equal "hell", s.to(-2)
```

Before the revert, this failed with:

```
  1) Failure:
StringAccessTest#test_#to_with_negative_Fixnum,_position_is_counted_from_the_end [test/core_ext/string_ext_test.rb:275]:
Expected: "hell"
  Actual: nil
```

This revert is to keep the functionality on `master` working.
If there is another way to get the performance benefit and keep
the documented functionality we can add that.

/cc @amatsuda @carlosantoniodasilva

I also extracted the tests from a single bulk method into a separate test-case.
The new tests cover the API described in the docs.

There are two skipped tests, which are broken as of 2ef1fb2c
* #to with negative Fixnum, position is counted from the end
* #from and #to can be combined

This was brought to my attention by #13627.

Closes #13627.

:mem_cache_store should receive a list of hosts or a dalli client,
otherwise raise it.
Also adding a changelog.

:mem_cache_store require dalli, rescue Dalli exceptions, and follow Dalli API.
Memcached gem, for instance, doesnt work anymore, as the API are different.

As we already require one client, we should make sure that client works, and not accept others, and if someone wants to use another memcache client they can write their own store adapter.