do not store commands list in MPD::Connection

it should have sent commandlist begin and end commands from the beginning,
having separated functions just to handle queueing commands was plainly ugly.

src/playlist.cpp

@@ -243,6 +243,7 @@ void Playlist::Sort()
 	
 	BlockUpdate = 1;
 	ShowMessage("Sorting playlist...");
+	Mpd->StartCommandsList();
 	do
 	{
 		for (size_t i = 0; i < playlist.size(); i++)
@@ -257,6 +258,7 @@ void Playlist::Sort()
 		}
 	}
 	while (playlist != cmp);
+	Mpd->CommitCommandsList();
 	ShowMessage("Playlist sorted!");
 }