Moved pathfinding code to aiPackage, implemented it's use with aiFollow and aiPursue
Changed implementations of aifollow/pursue/activate slightly, added ability for NPCs to go through unlocked doors (They even try locked ones), and step back from opening doors (Although it still needs some work)

Notes - When the door hits them while it's about to finish closing they will try to walk through the door.
      - Considerably more works is needed in making the NPC work out troublesome areas where they get stuck
Ensures destination is far enough to care about getting stuck