Changes
/* Colour Clash */
Possible resolutions on Spectrum:
* Remove colour from the display so that background and sprites use the same colours, clash is eliminated in favor to a "square shadow"but the game is monocolour..
* Move sprites in cell based movements. The colours still take priority but the clash is less of a problem.
* Add a black border around the sprites. Clash occurs, but because of the border it is not/less seen.
