Implement better error handling in mplayer interface class

[darkstar]

Currently Quasar barfs on every error it encounters with a dialog window in a very non-intuitive and obtrusive way. Either get rid of the dialog or change it to be more intuitive and of all things optional. Mark files that can not be played with an exclamation mark similar to i*Tunes. Also if mplayer quits unexpectedly during start up, retry to play the file. If it still won't work, let the user know what happened, but in a way that is unobtrusive.