add prev/next filter buttons as fallback
fix when state can be null
clean up
File picker: accept only images
Fix prev/next filter buttons so they get displayed in FxOS
fix btnGallery to use rems, simplify style, also make it obvious it can be clicked
initially hide gallery button
simplify CSS, load only one font (that's 158kB we don't load then!)
remove unused fonts from the repo too
show file picker button in static file picking page too