events show up for MPD pause,play,seek

See #329
MPD protocol improvements

 * lsinfo command allows '/' to mean root directory
   - closes #308
 * list command supports a single argument to return all tags of that
   type.
   - makes gmpc work for the artist view, genre view, and search view
 * when appending tracks with dynamic mode on, insert them before the
   random ones.
   - closes #266