* 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
With this change they now use `stdenv.mkDerivation` instead. Also some
minor cleanups such as URL fixes, adding version numbers, adding
descriptions, etc.
There are many more packages to fix, this is just a start.
Rules:
* Don't repeat the package name (not always that easy...)
* Start with capital letter
* Don't end with full stop
* Don't start with "The ..." or "A ..."
I've also added descriptions to some packages and rewritten others.
