Replace the `reset` module with a modern version based on
[modern-normalize](https://github.com/sindresorhus/modern-normalize).
The only things I removed from that module are the `font-family` rules
we don't need. Otherwise, it's similar to Fomantic's reset, but with the
legacy IE stuff removed.
I documented every change done to the module.
Also this introduces a new `--tab-size` variable but it has no real
effect on code yet.
