First working version of namd_colours.  Just minimap and no loading from file.
Minor change to variable initialisation, not needed but could be confusing.
Merge branch 'master' into named_colours
Added named colour support, configurable by xml data file. Currently just used by mini-map.
 * Merged with mainline
 * Fix for the skin shader
 * Fix for the map editor
 * Fix for the data dir