Start Menu, Piano, Music Player, Cannon (UI Practice)

In this web gl version for some reason, the brightness does not work. Sorry. The downloadable one has all functionality.  Now there is a music player with some tracks. Fully functional and with a drop-down to select whatever track you want. it is in the start menu after pressing start.  Updated piano and is playable because the keys are correct and there are enough of them. In C.  also added some …