Added Sprites and Comments

Modified one of the sprite files to have additional sprites including a
knight, helmet, skull, swords, and an axe.

Began Commenting Sprite, SpriteSheet, Tile, Player

Side Note:  we may have an extra unused sprite file. The
"spritesheet.fw.png" is unused as far as I can see (nothing happened
when I edited it), so I made all sprite changes from here on to
"spritesheet.png", but I still don't know why that extra one is there
(perhaps the result of the first save/save as?).