This feature allows the printer to read the filament diameter
automatically and adjust the printer in real time. Added code to read
an analog voltage that represents a filament diameter measurement. This
measurement is delayed in a ring buffer to compensate for sensors that
are a distance away from the extruder. The measurement is used to
adjust the volumetric_multiplier for the extruder. Some additional g
codes (M404, M405, M406, M407) are used to set parameters and turn
on/off the control. g code M221 is updated. Pins for RAMPS1.4, RAMBO,
and Printrboard are identified for analog input. The configuration file
is updated with relevant user parameters.