[TASK] Update OpenSans font, add WOFF2, remove SVG

The updated font should render special foreign characters (such as ä).
SVG fonts are deprecated, according to caniuse.com.
Upload generator_config.txt to FontSquirrel to see which settings were
used.
Merge pull request #2043 from jublonet/issue/3006-update-opensans-fonts

[TASK] Update OpenSans font, add WOFF2, remove SVG