Added support for M581 and M582 commands
M25 pause command can now be used inside a macro file to pause a file
being printed from SD card
Firmware update messages are now sent to USB and PanelDue (but the
existing PanelDue firmware doesn't display them)
Added gcode queue underrun counter, displayed in M122 Move diagnostic
info
M122 responses are now sent only to the comms channel that requested
them
Added support for additional firmware modules to be updated for Duet NG
Corrected a possible problem with multiple incompatible gcodes being
executed concurrently
Support H parameter on M0 and M1 commands
When executing M0/M1 commands and no print is paused, execute
stop.g/sleep.g if they exist
Treat M25 within the file being printed the same as M226
Added additional simulation modes to help identify bottlenecks
Don't disable all interrupts when starting a new move, to reduce
interrupt latency so that we can still receive data from PanelDue
Moved some utility maths functions to CoreNG
