- only for equality matching
- only components of ASN.1 types used in an X.509 certificate can be indexed
(composite types except for RDN and DN are not supported yet)
- how to use
index [attribute name].[component reference] eq
Ex)
index userCertificate eq
index userCertificate.toBeSigned.issuer.rdnSequence eq
index userCertificate.toBeSigned.serialNumber eq
index userCertificate.toBeSigned.version eq

2) attribute aliasing support
- x509CertificateIssuer
- x509CertificateSerial
- x509CertificateIssuerAndIssuer
3) AuthorityKeyIdentifier support(one of certificate extension)
4) Misc. improvement
- integrate OID and its decoder mapping table
- normalize and validate the values of both component asserions and
  extracted components
5) Misc. bug fix

GSER/BER decoders: return code and memory leackage

2) nibble type memory support when decoding
3) description type object identifier support
4) OPTIONAL, DEFAULT support in certificate decoder/extractor/matching
5) Misc bug fix

See "contrib/slapd-modules/comp_match/README" to understand
what's the purpose of  this patch is and how to use it.