NAME
        GetSprite -- Attempt to get a sprite for the simple sprite manager.

   SYNOPSIS
        Sprite_Number = GetSprite( sprite, pick )
            d0                      a0      d0

        WORD GetSprite( struct simplesprite *, word );

   FUNCTION
        Attempt to allocate one of the eight sprites for private use
        with the simple sprite manager. This must be done before using
        further calls to the simple sprite machine. If the programmer
        wants to use 15 color sprites, they must allocate both sprites
        and set the 'SPRITE_ATTACHED' bit in the odd sprite's posctldata
        array.

   INPUTS
        sprite - ptr to programmers simplesprite structure.
        pick - number in the range of 0-7 or
          -1 if programmer just wants the next one.

   RESULTS
        If pick is 0-7 attempt to allocate the sprite. If the sprite
        is already allocated then return -1.
        If pick -1 allocate the next sprite starting search at 0.
        If no sprites are available return -1 and fill -1 in num entry
        of simplesprite structure.
        If the sprite is available for allocation, mark it allocated
        and fill in the 'num' entry of the simplesprite structure.
        If successful return the sprite number.

   BUGS

   SEE ALSO
        freesprite() changesprite() movesprite() getsprite() graphics/sprite.h