How to install it?

[EUA]

There are no command about how to install it.

[ghost]

What do we have to do? How to use the monitor?

[devyte]

@mytrain the repo is missing the .jar or .zip. I only now noticed it because I tested the .zip that you linked to here.
Please either add the .zip to the repo or add instructions for creating the .jar from the repo source in the README.

[devyte]

Original discussion here.

[atesin]

HOW TO INSTALL GLOBALLY (on arduino ide v1.6.8+)

• download the zip from http://mytrain.fr/cms//images/mytrain/private/ESP8266SM.zip
  • mentioned in Arduino IDE Add-on : Serial Monitor for ESP8266 esp8266/Arduino#1360
  • maybe can also compile the sources from this repo, but i didn't tried and don't know which version is better
• open the zip and extract the contained folder (ESP8266SM) with full path to <arduino-ide-folder>/tools/
  • windows example: the full path should look like C:\Program Files (x86)\Arduino\tools\ESP8266SM\tool\ESP8266SM.jar
• restart arduino ide instances, the modified serial monitor should be under menu > tools