multiple musics

musics should be placed in the sounds folder and should be named
musicx.aiff where x is a number that identifies the song. the music is
chosen randomly between 2 right now so with more musics we need to
change the random interval in which the music is chose.
Merge branch 'master' of https://github.com/cruzas/tron_grid

Conflicts:
	main/trongrid.py