Fix the algorithm for is_stop

Previously the counter was incremented only once per cell (only each
time the main controller was called), so for the function to return
true, it had to read green color for three cells consequently.
Now it's the ColorReader task which update a counter.
Avoid a warning
Merge branch 'developer' of https://github.com/Oroles/MazeSolver into mapping
Merge branch 'mapping' of https://github.com/Oroles/MazeSolver into mapping