- Fix spacing on Windows and Linux in latest Firefox versions
- Tweak icon colors on Windows and OS X
- Adjust Z SVG to take up full height, so Z is a full 16px instead of
14px with slight anti-aliasing
- Use generated PNGs instead of SVG for Z toolbar icons, to remove the
need for complicated size rules
- Add separate platform-specific .svg files that are used by a
zotero-build script, make-z-icons, to generate the Z PNGs; the main
SVG is still used directly in the menu panel and customization
palette, with platform media queries to determine the coloring
