[mythtv] Minor bug in osd

[Paul Volkaerts]

Noticed the following which I don't think has any side-effects currently but
is incorrect...

In tv_play.cpp when you hit MENU it connects to certain signals from the OSD
but it only disconnects if you select an option in the menu.

If you exit from the menu using escape, it never disconnects.  If you then
hit MENU again and select an option, the "itemSelected" slot gets called
twice.

I think it needs a signal "treeQuit" so that tv_play can disconnect
properly.

Paul