* make font derivations fixed-output where applicable
* fix dead links
* `stdenv.lib` -> `lib` where `stdenv` is not involved
* remove `meta.platforms = [ unix ]` and `meta.platforms = [ linux ]` because the restriction has no sense for data packages
Some of these fonts are still available but their url has moved and
their hash has been changed. If anyone still uses them, feel free to add
them back.
