nanoReflowController

Added a startup autocalibration for main loop delay and to autodetect the main frequency (50Hz / 60hz).
Improved stability by changing the timerIsr period from 100us to 200us.
Added the PID_AutoTune_v0 submodule in case someone needs to automatically calculate custom PID parameters ( enable PIDTUNE in config.h, upload code and run autotune once, then disable PIDTUNE and upload again ).
Removed the fan option by default. Can be enabled again in config.h