implementation of pathfinding algorithm
Easiest way to test: Make a new empty openframeworks project and place main.cpp, ofApp.h, ofApp.cpp, tile.h, tile.cpp in the src folder.
'space': generate a new random grid
'd': show the 'cost' in steps from the start (blue square) to the goal (green square).
'c': 1 step in the cost calculation (default = -1); hold c until the start has a cost assigned other than -1
's': move the blue square one step closer to the goal.