Update build environment:

  default sysconfdir subdirectory is openldap instead of ldap.
    This removes conflicts with other ldap subsystems.  Should
    be configure option.
  *.conf files are now preserved.  A *.conf.default are always
    created with the latest conf.
  *.help and ldapfriendly are now placed in $(datadir)/$(ldap_subdir)
  updated man pages to reflect changes.