add hydrogel firmware as separate folder

Add fan support for donatello

fix 24V for a 12v ceramic heater -- fix PID control loop

update pid for donatello on hydrogel gel extruder (T1)

update donatello firmware and include calibration set

update config for don

Add z endstop and new config for donatello

Add really old rh-mac config

Add slic3r config

update configs and add dual extruder for calder

Update calder with acme rods

Sierra drivers

add calibration test set:

[Firmware] Add firmware for epstein + calibration

[Firmware] Add Calder json & distortion calibration