Sketch for the 28BJY-48 Stepper (and others)
[http://www.play-zone.ch/schrittmotor-stepper-motor-5v-1-64.html]
[http://www.play-zone.ch/schrittmotor-stepper-motor-12v-1-64.html]
[http://www.play-zone.ch/yfrobot-uln2003a-smd-motor-treiber-breakout-inkl-steppermotor-set.html]