Flash ESP8266

Connect Lolin via FTD1232:
D3 > G
RX > TX (FTD1232)
TX > RX (FTD1232)
G > G (FTD1232)
Use NodeMCU USB power conection

1. Erase the current flash
```esptool.py --port /dev/tty.usbserial-00000000 --baud 115200 erase_flash```

2. Write the new flash
```
esptool.py --port /dev/tty.usbserial-00000000 --baud 460800 write_flash \
  --flash_freq 80m --flash_mode qio --flash_size 4MB-c1 \
  0x0000 "boot_v1.6.bin" 0x1000 espruino_esp8266_user1.bin \
  0x3FC000  esp_init_data_default.bin 0x3FE000 blank.bin
```