Reset Calibration to Default menu option

[StefanTrethan]

I managed to to trap myself with false calibration settings that caused the iron to heat above 650°C for the 400°C step. It would be nice if there was a way in the software to reset cal without erasing the chip completely.

[PTDreamer]

If you want to try implementing this, in terms of the cal reset itself the functions to call are: resetSettings() from src/settings.c followed by NVIC_SystemReset() from CMSIS library.

On the gui to create a new option on the main menu you need to add comboAddItem(widget, "RST Settings", screen_whatever); to line 276 on settings_screen.c

You that need to setup screen_whatever which should probably have only a label ("Are you sure") and a yes and cancel buttons. Just follow the example of other screen_XXX.