Item12793: rework name clash resolution not to use DNs anymore

Item11632: fixed frequently corrupted cache

Item12365: fixed wrong encoding when accessing AD from utf-8 Foswiki

also: add support for ipv6



git-svn-id: http://svn.foswiki.org/trunk@17393 0b4bb1d4-4e5a-0410-9cc4-b2b747904278