terminal_colour() - return a wrapped and indented string where the driver
substitutes %^KEY%^ in the string with the matching VALUE of KEY in the
supplied mapping.


string terminal_colour(string, mapping, int | void, int | void);


string: to be parsed for '%^KEY%^' sequences
mapping: 'KEY:value' pairs
1st int: wrap after int printed symbols
if int < 0 fillout lines with blank's

wrap = 4:
wrap = -4:
'12 \n345 '

minwrap: 2

2nd int: indent by int blanks
maxindent: wrap-2

returns wrapped and indented string with each '%^KEY%^' replaced by KEY's value
or original string if no '%^KEY%^' sequence is found
(shouldn't it at least be wrapped and indented?)