- removed old two column selector in replacement of autocomplete list
- scales much better for alrge number of users
- still allows to select single users and user groups
- fixes#4291 (user group shows only username in members)
This fixes#3374. There's no good benefit of having possibility to prevent
setting disabled user from beeing an owner.
It can happen that we start preperating a system and use disabled accounts.
Also users shouldn't be forbidden to edit settings on an disabled owner.
