David Lowe
Modified phase table in stepper.cpp to enable stepping a bipolar motor using a twin H-bridge driver.
Fork of
stepper
by 
Kenji Arai
Corrected single-stepping, now walking up or down just one phase table. Compile-time options for driving bipolar motor in any of single-phase, two-phase, or half-stepping. Coils remain engaged at end of specifed movement command - de-energize coils by issuing a motor.move(0) while already stopped.