||- bullet|||- inv_formation|
||- enemy|||- gal_fromation|
base_image is the basic sprite class.
bullet, enemy, explotion and player classes are derived from base_image class.
inv_fromation and gal_formation are derived from formation class.
The gal_attack, text_msg, stars, and menu are independent.
For each class the first two parameters are RLE_SPRITE **dt and BITMAP *dst that hold the RLE_SPRITE * vector and destination BITMAP pointer.