samdb: add fullname_from_names() method
Add a method to construct the fullname, using the given name, the initials
and the surname.
If one of this values is empty, try to use the old one, given by an
attributs set.
If the combination is empty, the method will return the fallback-default
parameter.
Use this method to construct the CN or the displayName of users or
contacts.
Signed-off-by: Jule Anger <ja@sernet.de>
Reviewed-by: Björn Baumbach <bb@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>