* Use a simple optimization algorithm to compute a good set of XOR color pairs
* Algorothm is not very optimized (complexity is up to n^3). In practize, it stabilizes after 2 to 3 rounds of swapping colors
* Use this color table for all XOR effects
* Setting for grid color is now removed
git-svn-id: svn://pulkomandy.tk/GrafX2/trunk@2048 416bcca6-2ee7-4201-b75f-2eb2f807beb1