Admin interface: Set correct csrf tokens so groups and participations can now be deleted. Fixes #116

UX tweaks: Template jwinf: Enhance notes for logincodes, admin interface: Show less id and more information about student / teacher / admin status

Oauth login: Throw error instead of silently ignoring school information not being configurerd on teacher login via PMS

Enable configuration options to be passed through to certain (later possibly all) templates directly

Template jwinf: Optionally require field sex in profile, optionally allow 'no answer', 'diverse' or 'other', respectively, configurable via config file

Make admin interface select participations by session id instead of session token. This allows to show participations of users, that have logged out.

Add link to issue tracker and version number in footer (currently for logged in users only). Fixes #111 and #112

Ask users on OAuth login to fill in their user data (especially grade). Fixes #96. Also some formatting