- 2 new options for native mode (match whole words, do not highlight selections containing only whitespaces)
- new option to avoid highlighting text with less than the specified number of characters
- automatic black or white text color depending on highlighting color

- multiple highlighting capability added
- new option to keep highlighting upon click

- now provides a custom highlighting mode with the possibility to choose the highlighting color and to show search markers next to the scrollbar
- added context menu item to trigger highlighting

Full rewrite of the extension for Firefox 57.
Some options are no more available due to the limitations in the new extension framework (WebExtensions):
- setting custom keyboard shortcut (it is now Ctrl+F8)
- changing highlighting color
- tweaking text selection behaviour

The core functionality remains the same.