Univention Corporate Server 4.2 erratum 205 (bugfix)

This update addresses the following issue(s):
* The AD-Connector skips (re)recreation of UDM deleted objects.
* The error handling in the UMC module has been improved.
* Some objects were identified as the wrong object type. The identification
  handling has been fixed.
* It is possible to start the AD Connector service process in foreground.
* It is now prevented to start multiple instances of the AD Connector.
* LDAP operations are now correctly escaped in the AD Connector.
* Fixed errors in the SQLite escaping in the AD Connector.
* Fixed a deletion problem with nested groups in the AD Connector.
* univention-adsearch now accepts multiple attributes in the ldap filter.