Changes to allow stepper spindle to use per degree settings, ref. issue 926.
Changes for improved line number reporting for subroutines and branching gcode.
Some low-level ioport improvements, added definition for virtual pins/ports.
Deprecated direct access to number of the different ioport ports in hal.port struct, use ioports_unclaimed() instead.
Fixed incorrect comment string passed to passed to grbl.on_gcode_comment event.
Added generic redirector for temporarily changing input stream to read from a file. Supports nesting.