New class for AI control
An implementation of the A* algoritm

Given a start position, a goal position and a list of blocked positions
it returns the shortest (usually) path from the start position to the
goal position.

The return is a list of coordinates to go through to get the the goal
position, starting with index 0.
A simple class to test the implementation of the A* algoritm
Fixed an error in the calculation of the G cost
Refactored the check if a node is blocked or closed
Fixed algorithm, no corner cutting
Removed unused functions and added more comments.
Merge branch 'ai-path-finding' into develop