New RepRapFirmware 1.09h-dc42 for Duet electronics

Quote
dc42
Fixed print quality problems that mostly affected delta printers e.g. when prititng spiral vase cylinders
When reconnecting a browser, cancel any file upload from the same IP address
M111 now prints the number of each module with debugging enabled or disabled
In special moves on delta printers, the F parameter is now interpreted as the speed of the tower that moves the most
M114 now reports stepper positions as well as head position
Default to output in Marlin mode (because most host programs expect an "OK" response to gcode commands by default)
M104 command with no T parameter now defaults to the only tool if there is only one tool and it is not selected. On single-extruder printers, this works around a slic3r bug whereby the hot end temperature is set before the tool is selected or the start gcode is run.
When step errors are logged, report them immediately if Move debuggingis enabled. Also reports the total number of step errors in M122.
Changed interrupt priority to make tick interrupt higher priority than step interrupt, because we rely on the tick interrupt to check for over temperature conditions and kick the watchdog
Rewrote step ISR and related functions to improve maximum delta movement speed and prepare the ground for new pressure advance algorithms