Make Dragon Player use Phonon instead of xine-lib for DVD menus.

This long overdue patch drops all the xine-lib dependencies for Dragon Player.

DVD menu support (VideoWindow::toggleDVDMenu) is now implemented in terms of Phonon. This requires at least Phonon 4.5.0, otherwise the function will do nothing (which is the same thing it previously did when not building against xine-lib).

I also fixed a string in mainWindow.cpp which was referring to xine-lib. Distros backporting this patch may or may not want to skip this string change.

Builds in Rawhide: http://koji.fedoraproject.org/koji/buildinfo?buildID=263774

REVIEW: 6794
FIXED-IN: 4.8.0