Minor bug fixes: Homing travel calculations. Cycle resuming after spindle and dwell commands.

- Homing travel calculations fixed. It was computing the min travel
rather than max.

- Auto-start disable and pausing after spindle or dwell commands.
Related to plan_synchronize() function call. Now fixed, but still need
to work on the system state.

- Pushed a fix to make this branch more Arduino IDE compatible. Removed
extern call in nuts_bolts.c

- Updated the stepper configuration option of enabling or disabling the
new Adaptive Multi-Axis Step Smoothing Algorithm. Now works either way.

- Updated some copyright info.