MColourMode ;Returns value 4 which represents `colour' mode in the blit modes

For use with one of the `BlitMode' commands, such as MBlitMode, the MColourMode
function can be used in the same way as the default CookieMode, SolidMode,
InvMode and EraseMode. MColourMode is a new blit mode that will render the source
image to the destination so that all of the pixels in the source are of one
colour. That colour is specified with the MInk command. The colour-blit is based
on the shape's cookie which is turned into pixels of the ink colour and then
output. MColourMode performs a similar function to SolidMode, except that you can
define what colour the shape will be solidly displayed in. MColourMode can be
used with MBlitMode, MQBlitMode, MSBlitMode, MQSBlitMode and MMaskScrollMode.