Merge pull request #428 from wolfmanjm/upstreamedge

create an init() in main so stack is released
remove copies of steppermotor pointers in modules and use the ones in robot
add sanity check for exceeding base step frequency with actutor max rate and steps/mm
remove comment field
Merge pull request #429 from wolfmanjm/add/max-step-rate-check

remove copies of steppermotor pointers in modules and use the ones in ro...
fix race conditions in slowticker... thanks to raldrich for finding one of them