Multiple positioned lights
More on lights. Some tests
Merge. SingleColor class. Apple fix.

Really should have commited after merging. Here's a list of changes made
after merging:
* Added single color class that takes color as argument rather than
texture. This color is sent to programSingleColor in draw. It will now
be necessary to use this class, or a subclass, when using the single
color program.
* Rewrote the handling of apples so that apples aren't stored in the
allObjects vector while in the tree. Hopefully fixes problems we had
before.
* Apples now drop randomly. The player can still make apples drop by
colliding with the tree.