Adjustable motion timing (for testing) complete.

Added control of motion timing by using "[" and "]" to decrease/increase
wait time before continuing to move servos during a motion.

Added a potentiometer on analog pin 2.  It reads values between 1024 and
0.  That is divided by 32, giving 32 values that can be used as
servo_increment setting (also new) - this controls how many degrees each
servo moves before rechecking if it should move again (which remember is
controlled by "[" and "]").  So now I can adjust the pot to speed up /
slow down Rocco during a motion (primarily for testing smoothness).