Tidy up sevreal classes
Add checkboxmenu item
Change menu bar so plugins can add items.
Add update ID to notifications plugin
Fixes issue CLIENT-80
Change-Id: I289bbf7bcad6d9c528eb353dc8cf49ad48954a65
Reviewed-on: http://gerrit.dmdirc.com/1559
Reviewed-by: Chris Smith <chris@dmdirc.com>
Automatic-Compile: Chris Smith <chris@dmdirc.com>