To install:
Download the files in this repo to a local directory
Download and install Firefox
Type "about:debugging" into the address bar and hit enter
Click "Load Temporary Add-on"
Choose any file in this folder to load the extension
Now the extension is ready to use
To test:
Use Shift + Command + J to bring out the console
Develop guide:
https://developer.mozilla.org/en-US/Add-ons/WebExtensions