important.

- 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

back-hdb still needs work.

don't need to worry about them.

define OPERATION_BUFFER_SIZE for dummy Operations

remove syncrepl stuff from Operation struct