Improvements to the AI (AKA: NavMesh is harder than I thought)

In the last version we had some issues with the behavior of our NPCs, both the lights and the little black beans.

Those problems stemmed from underestimating the efficiency of NavMesh on a terrain. With a little more time I found how to clip better the terrain and bake a better navmesh, while also limiting the amount of agents simultaneously trying to calculate a route in real time. The result is better, although I still need to tweak it a little more. I think we need to drop the terrain and think of a better (less noisy) solution for the map, but that is something I have to discuss thoroughly with the rest of the team.