Once again AI export of radial gradients causes problems for
Chrome. What should have been a white-to-transparent gradient
became a white-to-black 90%-to-100% opaque gradient. So
hand-edited the SVG to remove the black orb floating in front
of their faces... pity.
Since this was done using guesswork these are not an exact match
for the png versions, but they seem close enough.
Tweaked svg_cleaner a bit to remove display none, add option to
strip whitespace. Stripping viewBox was too aggressive, two of our
emoji have non-default viewBox values, so emit it when x or y
are not zero.
Added script to invoke scour (now must be part of installation).