Initial combat implementation

Added a basic implementation for an enemy. The video is from a bug where several dozens more are spit out than needed. I've used a 3d model done in Blender real quick, as a placeholder.

When the enemy sees the party, it moves to be near enough of them to be able to attack. It doesn't really "follow" the party, it only moves to the last place where the party was seen, so the player can escape out of sight of the monster and avoid being followed.

 The attack logic for the enemies was already coded, maybe in a few days a complete combat could be played.