ESP8266: Flash images at more than 115200 bps

If esptool is limited to 115200 bps when flashing your firmware to an ESP8266, you can try to increase the bitrate by following the steps below.

1. Locate esptool.py for your installation. On Debian and Ubuntu, this file is located in /usr/share/esptool.
2. Edit esptool.py and change the value on the line starting with ESP_ROM_BAUD from 115200 to the maximum of 921600 or your preferred baud rate.