Start on css/colours module design.
A little start on Colours
Escape 19941 to $
Update doc to indicate 19941 -> $
Better handling of types when printing
Add typesafe max/min macros
Implement most of colours
Add colours header file
Some colour tests
Colour module reserved tests
Add (failing) colours:lightness/avg/lum tests
Whitespace, and make table_count static
Add new write_object method to generalise return type handling
Remove unused sym
Fix test 102s expectations