Corrects quick-hack version of border drawing: the assumption that the colour must be the same over a plotted period. Also corrects my entry for colour 15.
Corrects quick-hack version of border drawing: the assumption that the colour must be the same over a plotted period. Also corrects my entry for colour 15.

TomHarte/CLK,TomHarte/CLK,TomHarte/CLK,TomHarte/CLK,TomHarte/CLK