Hack prefs dialog into working.

For the minute this means the prefs dialog no longer
saves state, it also means there may be some layout
changes with the height loss and parenting change for
sub dialogs launched from preferences settings.

Change-Id: I9c46e6f03920866022cfe063c500f9523a11db6e
Reviewed-on: http://gerrit.dmdirc.com/3071
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Chris Smith <chris@dmdirc.com>