Nano ESP32 Native Bootloader Support

This release contains besides some small bugfixes support for installing MicroPython from the native bootloader on the Nano ESP32. This can be useful if your board does not respond anymore. In that case enter the native bootloader by shorting the B1 and GND pins.
The installer will flash a MicroPython firmware that also contains a bootloader plus a recovery image. The latter one is used to allow DFU uploads and also allows to switch back and forth between Arduino sketches and MicroPython easily. When running MicroPython, you can just open the Arduino IDE and flash an Arduino sketch by choosing the correct board and port.