Implement modal without bootstrap.js and jQuery
Accordion without jQuery / bootstrap js

it's not quite 100% as nice though
Remove jQuery and bootstrap js
Fix modal height and accordion in firefox
increase max height of accordion fields for mobile
Simplify usage of modal
Fix modal closing on mobile

Removing the click handler on the backdrop fixes it, because apparently
the inside listeners stop propagating. We should look for a fix on
backdrop clicking too. And we should also support clicking ESC to close
modal.
Remove now-obsolete toggle prevention function
Fix modal so that it reliably works on all plattforms
Close modal with escape key
Merge pull request #349 from glowing-bear/dejquery

[PLEASE TEST] Remove dependency on jQuery