s4:upgradeprovision - fix up the script regarding linked attributes

s4:upgradeprovision - fix up the script regarding linked attributes

We have to try to add new objects until between two iterations we didn't make
any progress. Either we are then done (no objects remaining) or we are
incapable to do this fully automatically.

The latter can happen if important system objects (builtin groups, users...)
moved (e.g. consider one of my recent comments). Then the new object can't be
added if it contains the same "sAMAccountName" attribute as the old one. We
have to let the user delete the old one (also to give him a chance to backup
personal changes - if needed) and only then the script is capable to add the
new one onto the right place. Make this clear with an exhaustive error output.

I personally don't see a good way how to do this better for now so I would leave
this as a manual step.