* Run screenshotter using Chrome 83 and Firefox 76
* Update screenshots
* Update NegativeSpace-chrome screenshot
The new screenshot is correct as per #1194.
* Update Units-chrome screenshot
The new screenshot is correct as per #732 and compared to Firefox.
* Update screenshots
The combination of jspngopt and pako should eliminate possible causes for
different PNG encodings, although the core reason for #325 remains unknown.
Pako has poorer compression rates than native libz, but optimization can
counter that effect, and actually reduce the size of the screenshots.
The screenshots for LimitControls and UnsupportedCmds on Firefox used to
exhibit subpixel rendering before, for reasons unknown. The regenerated
versions don't exhibit this. See #324 for a discussion.
