Missing unicode literal `u`
URL construction for extension-less files
Missing `only_conflicts` in template
Revert "Adjust following entries in moveEntriesBelow"

This reverts commit 68863de77f46ea9588733b218fcba9ed51cae840.
Fix assignment of avatar fields

Lists are returned for some fields
Fix cloning bookings
Temporary fix for Avatar creation

Authenticators don't seem to agree on how to send the user data.
Fix template when no deadline is set
Point assessment link to assessment page
Fix unbound local error
Fix calculation of conflicting occurrences
polib version bump
Escape colon (:) in preprocess_ts_string
Install only necessary jqplot plugins
Improve custom JSON encoder

* Rename class
* Handle date objects
* Add it to IndicoFlask
Add plugin hook for adding vars in vars.js

Also improve plugin_hook to handle no returned values
Generate vars.js cache file depending on plugins
Remove old statistics plugin
Add plugin_url_rule_to_js helper
Make url_rule_to_js consistent with url_for