MInk Colour.b ; Set what colour to assume as currently used. 0..255

Sets the currently used colour so that graphics operations can assume it rather
than you having specify a colour for every call. The colour should be from 0 to
255 inclusive. The ink colour will be used for a variety of operations, but note
that clearscreen operations (MCls) will always assume a colour of 0 as that is
more logical. The ink colour, prior to being defined by the programmer, will
default to 1.