Ensure menubar is hidden when running under Unity and using a Qt build that has not been modified for dbus-menu


git-svn-id: http://cantata.googlecode.com/svn/trunk@4111 b1e49159-3266-923f-9c3e-04f16369770a
...and the header!


git-svn-id: http://cantata.googlecode.com/svn/trunk@4112 b1e49159-3266-923f-9c3e-04f16369770a