Enable using multiple authentication backends.
(Samba-)AD and LDAP-Backends are implemented.
Session timeouts are implemented.

/close #17

/close #21

/close #86

If there are todos which have todo.who == current_user.username, show
only them, as there may be quite a lot of open todos in total.

/close #90

e.g. [todo:who:what]
e.g. [todo;who]

/close #95

/close #98

Create LocalTOPs when creating Protocols or DefaultTOPs, not on demand
when necessary, since that created double entries.

reference #96

/close #81

/close #77

/close #74

/close #71

/close #64

Categories can be set per protocoltype.
They are specified as another semicolon-separated argument to
[beschluss;…].
Decisions can be search for their category.
/close #53

/close #54

/close #57

/close #52

If the protocol is not on the same day, show a warning before pushing
the template to the etherpad. #44

/close #50

/close #39

/close #36
/close #28