Merge pull request #136 from csmith/master

Gradle version bump.
Update build scripts for artifactory.
Merge pull request #137 from greboid/master

Update build scripts for artifactory.
Synchronise selection events.
Merge pull request #138 from greboid/master

Synchronise selection events.
Remove the window menu.

This can easily be implemented as a plugin, and as I really don't
fancy fixing it this seems like the next best thing.
Merge branch 'master' of https://github.com/DMDirc/Plugins into windowmenusorting
Merge pull request #139 from greboid/windowmenusorting

Remove the window menu.
Update PMD to 5.2.2.