* Automatic Temperature:
* The hotend target temperature is calculated by all the buffered lines of gcode.
* The maximum buffered steps/sec of the extruder motor is called "se".
* Start autotemp mode with M109 S<mintemp> B<maxtemp> F<factor>
* The target temperature is set to mintemp+factor*se[steps/sec] and is limited by
* mintemp and maxtemp. Turn this off by executing M109 without F*
* Also, if the temperature is set to a value below mintemp, it will not be changed by autotemp.
* On an Ultimaker, some initial testing worked with M109 S215 B260 F1 in the start.gcode
* Automatic Temperature Mode
*
* Dynamically adjust the hotend target temperature based on planned E moves.
*
* (Contrast with PID_EXTRUSION_SCALING, which tracks E movement and adjusts PID
* behavior using an additional kC value.)
*
* Autotemp is calculated by (mintemp + factor * mm_per_sec), capped to maxtemp.
*
* Enable Autotemp Mode with M104/M109 F<factor> S<mintemp> B<maxtemp>.
* Disable by sending M104/M109 with no F parameter (or F0 with AUTOTEMP_PROPORTIONAL).