NAME
    AllocRaster -- Allocate space for a bitplane.
SYNOPSIS
    planeptr = AllocRaster( width, height )
       d0                    d0:16  d1:16
    PLANEPTR AllocRaster(UWORD,UWORD);
FUNCTION
    This function calls the memory allocation routines
    to allocate memory space for a bitplane width bits
    wide and height bits high.
INPUTS
    width   - number of bits wide for bitplane
    height  - number of rows in bitplane
RESULT
    planeptr - pointer to first word in bitplane, or NULL if
               it was not possible to allocate the desired
               amount of memory.
BUGS
SEE ALSO
    FreeRaster() graphics/gfx.h