StarlingCamera - part 2

- re-arranged code more logically, made more room for rotation.
added aabb and tests, renderDebugDraw helps visualize more what's going
on (but still isn't exact anyway - something is wrong with the overall
rotation or scaling.)

- added createAABBData to MathUtils in order to get the relative
position of the bounding box via offsetX and offsetY so we don't have to
calculate them again when fetching our AABB. up to now, I find it will
be helpful for the camera.

- StarlingArt DebugArt has rotation through cameraLens.