Console output of mpg321

Play all audio from a single card with a single call to mplayer.

Normally, audio and video files are put in a queue and played one after the other.

But i sometimes like an audio file replayed immediately, even before the first playing is finished. This makes that work. Just hit r or F5.

This add-on has not been tested on all platforms. It may not work when the only mplayer available is the one from a binary Anki installation.