lists: creation, invitation, item deletion: this big patch includes: - reorganisation of pages for consistency, discovery is now the main list page, and list overview is now in `view` while item view is moved to `view_item` - lists from lists of interest are now shown in discovery page - list deletion from discory page - list can now be created, using templates now available from backend - invitation manager can now be used from list overview - list item can now be deleted from `view_item`