This is just an IntelliJ refactor, using EventBus in place of
DMDircMBassador whenever possible.

Stop swimming against the tide and accept what most of the rest of
the world does.

While it adds an annoying depth to the actual source code, it makes
the root directory nicer (no more 'test-res' dirs), means we don't
have to override the gradle config, and makes it nicer to work in
IDEA 2016.1.

In preparation for child eventbusses being removed, anything
trying to subscribe to specific windows now needs an explicit
check.

In the process, fixed two issues:

- channel who plugin was sending way too many requests - each
  connection was querying every channel in the client. i.e.,
  with 5 servers open there'd be 5 WHOs per channel...

- ServerFrame stops itself listening when *any* frame is closed.
  So closing a channel window then reconnecting wouldn't offer
  an SSL dialog, because it's already unbound the listener.

Issue DMDirc/DMDirc#662

* Move all plugins to their own top-level directories.
* Move resources out of source trees
* Add Gradle build scripts.
* Remove ivy and ant build scripts.

Change-Id: Ib69a48ef26800c174ccf51c84ff9d1f73529460f
Depends-On: I303b6b69518468f98d48d835b8f40135d9e4bcbf
Reviewed-on: http://gerrit.dmdirc.com/3850
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>