Fix -playmusic command line option not working

There's a bug where playtesting from Ved doesn't properly play the music
of the level, due to no fault with Ved.

This was because the music was being faded out by
scriptclass::startgamemode() case 23 after main() called music.play().
To fix this, just call music.play() when all the other variables are
being set in Game::customloadquick().

desktop_version/src/Game.cpp

@@ -5163,6 +5163,7 @@ void Game::customloadquick(std::string savfile)
         saverx = playrx;
         savery = playry;
         savegc = playgc;
+        music.play(playmusic);
         return;
     }