Mobile interface

While the current website can be opened on a mobile phone webbrowser, it is far from ideal.

This PR contains a number of optimisations to make the site fully usable on mobile:

• Scale is optimised for mobile screen.
• Sidebar can slide out of the view.
• Sidebar moves to bottom om portrait screen orientation.
• Tables and other elements adjust to available space.
• The site can be installed as an hybrid app without browser interface.