INT-3511: Document WebSocket Support

JIRA: https://jira.spring.io/browse/INT-3511

Add note about Broker destinations

Doc Polishing

INT-3511: Fix 'useBroker' Docs and provide compatibility with SF 4.1.1
INT-3524 Fix Tooling MessageChannel References

JIRA: https://jira.spring.io/browse/INT-3524

A number of references (expected-type) still referred to
the Spring Integration 3.0 MessageChanel.
INT-3526 Used Expanded URI In Exception Message

JIRA: https://jira.spring.io/browse/INT-3526

Previously, the URI in the exception message is the raw
URI with placeholders, if present.

Use the expanded URI in the message instead.
INT-3512: Add `<advice-chain>` to the Aggregator

JIRA: https://jira.spring.io/browse/INT-3512

INT-3512: Fix typos

INT-3512: add `expire-` prefix to the advice sub-elements

INT-3512: Mark `AggregatorWithCustomReleaseStrategyTests` as `LONG_RUNNING_TEST`

Doc Polishing
INT-3527: WebSocket and 'o-c-a' Improvements

JIRA: https://jira.spring.io/browse/INT-3527

* `WebSocketInboundChannelAdapter` now handles `CONNECT` STOMP message and sends `CONNECT_ACK` message to the `WebSocketSession` immediately
* `ExpressionMessageProducerSupport` implementations now checks the result of `expression` and if it is a `Message<?>` it is sent to channel without creating a new one
which previously wrapped that `Message<?>` as the `payload`.
* Add `<script>` support to the `<outbound-channel-adapter>`
* Upgrade to the SF 4.1.1
* Add appropriate notes to the Docs
INT-3528 Use Collections min and max methods where appropriate

JIRA: https://jira.spring.io/browse/INT-3528

Use `min` and `max` methods instead of sorting an entire collection to get the minimum or maximum element.

Change other inline `Comparator<?>`s to the `final` fields
INT-3531 Varargs for JavaMailSender

JIRA: https://jira.spring.io/browse/INT-3531

JavaMailSender now uses varargs instead of [].

Also, add spring-context-support as an optional
dependency to avoid reactor pulling in an old version into
the eclipse .classpath.

You cannot exclude transitive dependencies from optional
(reactor) dependencies.
INT-3529 Add 'expire-groups-upon-timeout' to Reseq

JIRA: https://jira.spring.io/browse/INT-3529

Late arriving messages will now be immediately discarded by
default.

INT-3529 Polishing

Move group completion to the Resequencer's `afterRelease()` when
the group is timed out.
Increase `receive` timeout for some tests

https://build.spring.io/browse/INT-B41-118

Since `send` to the `discardChannel` caused from the separate Thread (`TaskScheduler` from `groupTimeout`)
there is some time window when receiving thread wait on `queue` lock, so `0` timeout to wait isn't enough
Fix Docs issue

https://build.spring.io/browse/INT-B41-119
INT-3521 `completions` for ChannelInterceptorList

JIRA: https://jira.spring.io/browse/INT-3521
INT-3521: Rework invocation `index` to the `Deque` of invoked interceptors