new: cross-platform compatibility
new: Firefox support
new: Settings import and export (thx @JWCS for request #242)
new: add "translate" as support option
new: double-clicking scroll-to-top button reloads the page (thx @neoIDjoe for request #244)
fix: some buttons in settings not accessible by keyboard
upd: settings style
upd: Dutch translation (thx @Vistaus ♡)
upd: German translation