bulletin.knob.nl website update

The Bulletin website is refreshed. These is are the most important changes:

• most recent version of OJS (Open Journal Systems)
• simplified and neutral URLs (DOIs have not been changed): bulletin.knob.nl
• prominent graphic representation of the recent issue on the home page
• 'Polaroid' representation of the back issues in the 'archives'
• 'hamburger'-menu for small screens 
• integration of social media in each issue and all articles