Some ttf fonts used to sign are shipped does not come with a clear
licensing. Also some of them does not have accented characters.
With this commit, they are replaced with better ones and their
accompanying Open Font License.
Also, before this commit, any file in the font directory was read to be
rendered by the sign widget. With this commit, only `ttf`, `otf` and
'woff[2]' files are read, this allows to store the license file
alongside with the font.
X-original-commit: f4a9aec57b871806fb225bf91a941edb0fde5cbe
Christophe Monniez
bc1a017bb8