Chests and stuff

+ added sounds for events
= all sounds need to equalized; i.e. some sounds are louder than others
+ added chests; when the player is close to a chest, just tap the player
= it's a little buggy opening multiple chests
+ added main game music
= the sound that plays when a player can get hurt needs to be on the
same timer as the damageTimer
+ added ghost proximity alert in back-ends; not entirely implemented

- tweaked spawning code