libsaria: Set volume callback

libsaria/callbacks.py

@@ -18,3 +18,7 @@ def load_file(file):
 on_like = null_cb
 def like_song(like):
 	on_like(like)
+
+on_set_volume = null_cb
+def set_volume(prcnt):
+	on_set_volume(prcnt)

libsaria/controls.py

@@ -91,7 +91,8 @@ def seek_backward():
 	libsaria.audio.seek_sec(-5)
 
 def set_volume(prcnt):
-	return call("SETVOLUME", audio.set_volume, prcnt)
+	audio.set_volume(prcnt)
+	callbacks.set_volume(prcnt)
 
 def set_rand(rand):
 	prefs.set("libsaria.random", rand)