FR: changing heater power based off of temp power curve of a PTC hotend

[Nathan22211]

at the very least this should aid with the issues these types of heaters have. I don't think using a formula will work too well here as it seems they don't follow a general curve in some cases. What might work better is having an option called heater_power_xxx with the x's being the heater temp. You allow for multiple of these when MPC is used and it'll change the heater power setting when it gets to that temperature.

the only other alternative I can think of would be making the heater power editable during runtime with a command, that way it can be used with the filament density macro and whatnot

[rogerlz]

Another alternative, which is already being worked on, is pid(heater) profiles: #351
similar to pid, you will be able to have multiple heater profiles and can load them with a gcode command