Don't pass WindowManagers to FrameContainers.

Change-Id: I0f60ac23438313cab49cdb86c089938f5ee44abc
Depends-On: Iadbca8a28f7ef3372df7fda722a3cbba2a0fbad6
Reviewed-on: http://gerrit.dmdirc.com/2843
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>