Add event methods and tests

Depends on PRs:
- [x] #6 
- [x]  #7  
- [x] #8 

This PR adds View Online page functionality and Links to navbars/locations functionality

Tests will fail until Prs 7 and 8 get merged
Well theme stuff isn't inherited though. And we shouldn't inherit. The admin should add an icon to each style's theme folder, especially different icons (same name, different look) if the themes color schemes are totally different. So all we're doing here is checking if the icon exists for a given user's style, let's use it, otherwise fallback to the theme's default icon, which comes from the them anyways using the icon-pages class that is part of phpBB.