AI Redesign

No new content added. In this new build I have completely redesigned the droids' AI using behavior trees and also tweaked their movement.  The most notable change is their movement. Originally droids used a navmesh at all times which would sometimes cause odd behavior like circling collectible objects/player.  Droids could not drop to lower elevations unless in specified areas which added a lot of time to level designing. Now droids will only use a navmesh to move into position to carry a collectible. When following the player they will use a VERY basic follow script (almost literally just a Vector3.MoveTowards), this allows the droids at a higher elevation to drop down to get to the player. You probably won't notice much with the new behavior tree but this makes bug finding/fixing a lot easier on my part, it also makes adding functionality a lot easier.