feature request: Add the font "Hack"

[MartinMSPedersen]

The font hack is great for code and different from the other fonts included in codeprinter. github page homepage

[MartinMSPedersen]

btw thanks for this program

[jaredpetersen]

Looks like this wouldn't be too difficult to add and I'm open to more fonts.

We'd add the font stylesheet here, add Hack as an entry here, and update tests.

I'm swamped right now but would be open to do all the release stuff if someone was able to put up a tidy PR.