Add possibility to have an 'anchor'

[mvriel]

On cloud workers it is not relevant where the origin is as long as the given game objects are within the given Dimensions. For Clients it would however be better if the centre of the new position tries to match an anchor (usually the Camera or player object) as much as possible.

This is nice because floating point imprecisions may be visible at the edges of the dimensions (depending on how large of an area you set) and by preferring the anchor to be in the center of the shift area it will have the least jitter.