Configure the window
Added colourUsed helper method
ColourProxy should know if they are placeholders of if they have been coloured
Default to 0 if given value is less than 0
Equals method for ColourProxy

Never though I would ever actually need an equals method outside of
OOPD110, but hey, look at this :P
Add `add` helper method to ColourProxy
RelativePosition for semantics sake
Store the width & height in what amounts to a constant
Actually look at the relative position