More spells

Added some spells. Now there are two kinds of "damage" spells, one "stat" spell, and lifesteal. With these, you can think this game has strategies :D

One more weapon, the knife, still work in progress: it has a quick ranged attack and a slow heavy attack as standard moves, and no other moves for now. It also has no sound at the moment.

The enemy "AI" is slightly better. Now they won't stand next to you whitout attacking.