Temporary fix for RTD temperature spikes causing failed prints
Added 'only if printing a file' condition in M581 command
Fixed M117 for PanelDue
Don't print extruder positions in M114 because they are always zero
Process M0 and M1 when in simulation mode
Allow setting of fan PWM from 50% upwards when a fan is in thermostatic
mode
Reduced default extruder heater PWM frequency
Axes are no longer homes when microstepping is changed
SD card interface speed is included in M122 output
