Added collision handling to player.

Signed-off-by: Hin Lam <max21226@Hin-Lams-iMac.local>
Performance fix.

Signed-off-by: Hin Lam <max21226@Hin-Lams-iMac.local>
Merged in latest circle branch from Hin.  Includes
collision handling on the circle-based implementation.

Merge remote-tracking branch 'max21226/circle'

Conflicts:
	sources/GameObjectPlayer.m
	sources/common.h

Signed-off-by: Matt Cleveland <mgcleveland@gmail.com>