Added a new Tile display for On-page links. The new layout can be selected in the extension's main settings menu.

Got rid of the first-version legacy — presets and buttons fully moved to the JSON format
Added export/import of custom settings and restore of the defaults
Settings can now be loaded from a URL — handy when you want identical settings on all your computers (host the JSON on your server and load it hassle-free)
Added a button to the extension popup that adds the current page to a preset's buttons
Each preset now has default button settings, so new buttons appear in the places usual for that preset