BUGFIX: robot now spins in the direction you asked it to, instead of the opposite direction
BUGFIX:  Encoders now correct reset their counts to 0 when you ask them to
BUGFIX: set encoder direction in spins to the same directions as the motors

FEATURE: added spin_test() to test spin accuracy
FEATURE: added movement_test() to test encoder accuracy
FEATURE: added forward_meters() and backward_meters() incremental moves
FEATURE: spin_meters() and is_done_spinning() now actually spins the # degrees you wanted
FEATURE: added a NONE direction to directions_t enum