MReserveBitmaps [(]NumberOfBitmaps.w[)] ; Reserve structure-memory for Bitmaps

This must be called before any operations are performed that have anything to do
with chunky Bitmap objects, unless making use of the default reserved chunky
Bitmaps. A chunky Bitmap is one of Mildred's `bitmap' objects, akin to a normal
blitz bitmap except that they hold different information and the graphics are
stored in a different format (chunky). Using this command does not allocate
space for any shape graphics, but does make space for the shapes to be created
and stored. Chunky Shapes are numbered from 0 upwards. If used as a function,
this command will return the address of where the chunky Bitmap objects
(structures) are being stored, or 0 for failure.