64 bit fixes.

Finally picked up a 64 bit iOS device last week and found out there were some problems in both Chipmunk and Cocos2D. I was sort of surprised since both have been running on 64 bit Intel for a while. There were actually a few fairly serious bugs.

I figured these changes should get reviewed by at least one other person before merging:
* Fix all the warnings when building for 64 bit.
* Update the deployment target to 5.1.1 as required by the 64 bit arch.
* Make sure there are casts to all objc_msgSend() and method imp calls.
* Fixed a few bad pointer casts (GLfloat * to CGPoint *, etc)
* Updates the Chipmunk reference where I fixed a number of similar issues there.
* Make it optional to run the physics using float32 on 64 bit for a mild, but reasonable performance bump. Most of the diffs are for this. (defaults are still to use CG types for convenience)
* In general, make a better separation between CG and Chipmunk types.