Add possibility for dash in course code

This prq adds the possibility for course codes such as `INF-MAT2000`.

This fixes #299 .
What's the reason for having parentheses here? They cause an issue in the code on line 142, where the regex is placed within [ and ]. When parentheses are enclosed in [ and ] they actaully mean literal parentheses.

This causes an issue with articles like "TDT4180: Menneske-maskin-interaksjon (MMI)", which will now have parentheses show up in the URL and in their cache key.