Some refactoring

 - Made imports from `utils` relative to avoid picking up any system wide `utils` modules
 - Made naming of `color` and `colour` standard to `colour`
 - Added `black` and `default` to the list of colours
 - Made `default` the default colour (can't assume the users background colour will be black)
 - `printcolour` gets the escape code from `get_colour` instead of expecting one to be passed in
 - Other small refactoring