Optimize2

This optimisation makes each Bridge object keep track of the current lamp states, and filter out redundant lamp instructions. Since the Hues bridges don't filter redundant instructions themselves, and instruction capacity is quite limited, this patch should improve performance significantly.

Once this feature is applied to the lamp servers, the game and application programmers won't have to think about this particular performance issue. They can simply paint the lamp pixels as much as they want and let the lamp server do the filtering.