SNAPSHOT:
 - refined move_machine_queue() skeleton
SNAPSHOT:
 - moved machine mirror math to gcode-math
 - Makefile dependency refinements
SNAPSHOT:
 - moved more math from gcode-machine over to gcode-math
 - added call to move_machine_queue in gcode-canon
 - removed unused feedMode member of TGCodeMoveSpec
SNAPSHOT:
 - null-move detection was wrong for move_machine_arc
 - queue initialization was wrong