general code refactoring of LDAP authentication backend: use Net::LDAP::Util::escape_dn_value for escaping the login, pass gid to VM when available from LDAP user entry, handle scope attribute which was being ignored, simplified loging messages, differentiate between empty and undefined settings, several documentation fixes, mostly untested

git-svn-id: https://svn.qindel.com/repos/main/projects/qindel/QVD/src/trunk@21701 4046b530-fbad-4e16-af16-ee11f0b55167
make auth.ldap.bindpass configuration parameter optional

git-svn-id: https://svn.qindel.com/repos/main/projects/qindel/QVD/src/trunk@21724 4046b530-fbad-4e16-af16-ee11f0b55167
substitute %u on filter

git-svn-id: https://svn.qindel.com/repos/main/projects/qindel/QVD/src/trunk@21727 4046b530-fbad-4e16-af16-ee11f0b55167