more fixes to search permissions:

more fixes to search permissions:
- require that for links and multilinks the searching user has access to
  at least the orderprop, labelprop, and ID of the linked class
- allow combinations of roles: we previosly required that for transitive
  properties all elements where searchable by the same role. We now
  allow that the roles can be different for each property. This allows
  assigning different roles to different sub-systems and allowing users
  having all required roles to search across subsystems.
- regression test updated
- fix doc/upgrading example for new signature of roleHasSearchPermission

git-svn-id: http://svn.roundup-tracker.org/svnroot/roundup/roundup/trunk@4553 57a73879-2fb5-44c3-a270-3262357dd7e2