Re-factored the code for calculating movement, by introducing a new method for calculating the heuristic distance to the target, and storing the distance of each cell by trial and error through a for loop for the 3x3 grid of cells available for movement around the Unit.
Re-increased the delay between frame updates to 1000ms.
Finally implemented a successful first draft for the Unit to follow a straight line to it's destination. Also first minor iteration for the weighted cells. So far, only gradient and distance-to-target are implemented.