Make IDEA warn about silly MBassador calls.

If post() is used without the result being dereferenced, flag it
as a warning.

Change-Id: Id536f2cb5c31de9f13008d0519069965637ae754
Reviewed-on: http://gerrit.dmdirc.com/3781
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Automatic-Compile: DMDirc Build Manager
Add test for ChildEventBusManager :)

Change-Id: Ieda960d247a8ba1a78391043b39052001ce8a6a5
Reviewed-on: http://gerrit.dmdirc.com/3782
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Automatic-Compile: DMDirc Build Manager