Created world position component that allows getting the world position (as opposed to the local position).
Used that component in several places to use world position and not local position.
Added a target position property to the built in camera to allow control over which point in the target itself the camera should focus on.
Refactoring- renamed hit-test bounding box and render bounding box to world bounding box and viewport bounding box. Added a property for getting the world bounding box which doesn't require passing in the viewport.
Fixes #271