move external coloring engines into track-hacks plugin
|Reported by:||Owned by:||Remy Blank|
Phased out the SilverCity-based highlighter by moving it to
Enscript, SilverCity and Colorer are all external engines that can be conveniently abstracted by one Trac-Hack plugin. Now with official native Pygments support there is no need to keep their supplementary code in distribution.