Bug fix: Pause function sometimes used to hang while running pause macro
file
Don't wait for all moved to complete when executing a G92 command that
just resets extruder positions
M574 endstop configuration now overrides M558 when determining whether
or not to use the Z probe instead of a homing switch
Added XYZ parameters to M667 command to support CoreXZ etc. machines
with paired axis ratios that are not 1:1
Minor change to step ISR to improve timings and service drives in
round-robin order
