Support non-static PopupManager.

Change-Id: I5c463bfe8a56546b5021928458bc0e2ffae43836
Depends-On: Idbed116f8774b0be617c7123b1a35f52133cdac5
Reviewed-on: http://gerrit.dmdirc.com/2912
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Automatic-Compile: DMDirc Build Manager
Initial foray into Swing UI DI.

Add a SwingManager to manage the injected content - eventually
this will become the SwingController.

Change-Id: Ie923301c00e0166792326f48beff25b5e59c42fa
Reviewed-on: http://gerrit.dmdirc.com/2913
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Automatic-Compile: DMDirc Build Manager