NPCs now only attack enemies within a radial distance (rather than
square).
Combat dummies are now invincible.
Removed one NPC.
A lot of Hero code now moved to RPGEntity class since this should be
common.
Moved OnInteract code to NPC.
Numerous Improvements and Refactoring.
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- Moved Approach function to RPGEntity.
- NPCs now try face the direction of the player OnInteraction.