Add NameAndOptionalUID/UniqueMemberMatch handlers

Need to add entry_decode().

Validation is quite rigid allowing use of simple normalization
and caseExactIA5 matching (and indexing).

brain-damaged LDAPv2 clients.

back-ldbm needs modification to support db home directory as backend
(as oppose to database) option.

Good for nss_ldap (equality indexing of uidNumber and the
like now work).

Shift burden from INSTALL/Quick Start to install chapter
Clean up example LDIF

Add "disallow tls_authc" to disallow StartTLS when session is authenticated.
Create and use connection2anonymous routine for consistency.