cleanup: remove couple overlooked lines

cleanup: rename class name

cleanup: remove duplicate route

cleanup: move jsroutes generator function and only generate in debug mode

refactor: made javascript routes autogenerate based on python routes

admin: in usergroups admin allow prefiltering the list of users based on an autocomplete query. also updated a couple tests which were not testing correct response.

style: make arrows in usergroup members selector easier to press

bugfix: santize wouldnt allow files starting with . - fixes #3936

authn: Fix handling of form errors and default values.

tests: Adapt test to changed template.