Create effects on the same virtual desktop as the creating pony.

When creating an effect window, read the _NET_WM_DESKTOP property from the
creating pony's window and set the effect's property to the same value.
Don't show speech bubbles in the task manager.

Qt seems to forget the _NET_WM_STATE property set on the speech bubble at
creation. Instead, set the property before showing the bubble each time
the pony says a line.
Merge remote-tracking branch 'creideiki-remote/master'