Pull-request-1: author:mxlshk, engines testing.
Pull-request-2: author:mxlshk, naming fixes.
Pull-request-3: author:mxlshk, delay and input fixes.
Pull-request 4: author:mxlshk, color sensor test.
Pull-request 5: author:mxlshk, global colorBlocked variable.
Pull-request 6: author:mxlshk, refactored_main.ino + backward_echo handled.