This change fixes how DNs are serialized into BER for SearchRequest messages.
It drops spaces around commas, since it breaks some LDAP servers that expect
the DN to be separated by comma only as per RFC 4514. The old format of
spaced separators from LDAPv2 is thus no longer used.
For #611
- Add 'spaced' function to DN objects allowing toggle of inter-RDN when
rendering to a string. ('dc=test,dc=tld' vs 'dc=test, dc=tld')
- Detect RDN spacing when parsing DN.