audio: Add support for gapless playback

By responding to the about-to-finish signal. If it looks like we're
about to pause, then we let the EOS handler handle it instead.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

audio/player.py

@@ -21,6 +21,12 @@ class Player(bass.BassPlayer):
         if self.track:
             self.track.add_to_playlist("Previous")
 
+    def do_about_to_finish(self):
+        if self.Autopause.get_value() != 0:
+            (track, cont) = tagdb.Stack.next()
+            self.emit("track-changed", self.track, track)
+            self.Autopause.decrement()
+
     def do_eos(self):
         self.next()