Initial Pathfinding code

This code is non-functional, but I'm committing it to this branch
so that it can be tranferred between machines.
Add cleaner neighbor processing and fix some issues

Mysteriously, this will crash your chrome tab right now
Fix and reconstruct the path found
Reference atGoal through a callback for future generalization
Provide a conversion from world data to path data
Super Simple path renderer
I should probably actually return the path
The open list always should have been a min heap
Include the starting position in the path
Move addition of Gcost for easier function changing
Refactor path reconstruction
add path renderer which accounts for corners and such
Merge branch 'pathfinding'