Once the VSprite has been added to the GELs list and is in the display,
some of its characteristics can be changed dynamically by:

    * Changing y, x to a new VSprite position

    * Changing ImageData to point to a new VSprite image

    * Changing SprColors to point to a new VSprite color set

Study the next two sections to find out how to reserve hardware Sprites
for use outside the VSprite system and how to assign the VSprites.