MUseShapeBank BankNumber.w ; Current shape bank, 0..31

In Mildred there are currently 32 built-in `banks' of Shapes. When you reserve
some shapes with MReserveShapes they usually only use bank 0, but if you wish you
can use *seperate* sets of shapes in banks numbered 0 to 31. You should `use' a
bank before reserving shapes. Note that operations accross banks are not possible
and a current Shape number of 5 means chunky Shape 5 in the `current' bank.