added auto-rotation support
support radians instead for rotation

this makes things a lot easier.
added bouncing guy
support initializing angleRadians on Entity
added support for destroying entities
added Entity.onInit support

this allows one to define code that runs when the entity is created,
after it's been initialized.
changed the keyboard driver behavior

it now stores some state information for better handling of turning
stuff
added a gun in the middle! woo.