Hampton Court Maze Solver

Jens, thank you for your inspiring 'Single Sensor Car'.
Thanks also go to the late Jerome K Jerome for giving me a clue as to how one can survive in a maze such as this.
I have slightly modified your code to build a solver for the maze at Hampton Court near London.

Improvemts:
1.
I feel that there should be a way of indicating that the little red bug (bot) has visited the middle of the maze and returned to the start, perhaps two trigger sprites and a counter to show the number of times the little creature has completed the puzzle.
2.
Bot sometimes gets a little lost and loops back on itself, notably in the top right where I have thickened the end of the line. I feel my fix is a bit of a cludge, sort of like changing the world to make the code fit.