Hi Robin the zip file is the complete sketch and the latest version. All of it. Did I forget anything?
The link you provided made a lot of sense. I thought I needed the accelstepper.h to get an acceleration working. Actually, that code of yours, to me, is readable and I understand what is going on.
I now have to figure out if I can get that to work in my sketch 
Thanks.
ETA:
Does this also work with two steppers running at the same time at different speeds?