Tracking issue for AI (for enemies and NPCs)

Some things that AI should do, but don't currently do.

• Some NPCs and species of animals should run away when under attack.
• NPCs should run away when low on health.
• Guard NPCs should respond when their fellow villagers are under attack.
• Enemies in dungeons should work together when fighting.
• Enemies with healing abilities should be able to heal their allies. (There are currently no enemies with healing abilities)
• Ranged enemies should not shoot their allies when they get in the way.
• NPCs that are offering a quest should approach the player and say "I need [quest]. Can you help?"
• NPCs that are offering trades should approach the player and say "I'm selling [item]. I have the best prices around!".