The required version of fontforge (from 2020!) is not available in many
distros. This is an annoying for contributors and greatly complicated
the CI and F-Droid scripts.
The generated font file is now included in the sources. Fontforge is
still needed when adding new glyphs but this is not a common operation.
The accents are taken from the Roboto Regular font (Apache 2.0), added
the dotted circle and exported with FontForge.
The argument to FontForge's Import function are changed, the fifth
argument controls the accuracy and needed to be lowered otherwise the
grave accent wouldn't be rendered at all.
Keep the glyphs in SVG format and build the font using a FontForge
script.
A part of the previous font is kept because the sources is lost.
This adds a new dependency to the build system, fontforge.
