class type auth_method =object..end
auth_method object represents a method of authentication. Such an
object can be shared by several clients.method name : stringmethod new_session : t -> string option -> auth_protocolNone
if the default is to be used (whatever this is). Some
authenticators only support None.
It is allowed that the returned auth_protocol object is already
in state `Done, i.e. that actually no protocol is run.
Changed in Ocamlnet-3.3: different signature. The user name is
now an argument, and the method returns auth_protocol instead
of auth_session. There can now be a separate session for
each user (plus for the default user None).
