ESP32 NodeMCU v1.2

ESP32 in NodeMCU pin compatible form factor, intended for upgrading existing PCBs.

I normally upload new firmware through OTA and really did not have any use for onboard USB, so I included a sonoff style 5-pin serial header instead.

Since the ESP32 has excellent GPIO pin remapping flexibility, I did not duplicate the serial pins into the main NodeMCU pins, but rather used other universal pins.

I did not attempt to match pin numbers with NodeMCU, since they behave differently to ESP8266 anyway, for example GPIO12 is generic on ESP8266 but has special function on ESP32. I stayed away from all ESP32 strapping pins, since it has so many generic pins anyway, and it's so easy to remap in software.