Added accessor method to help out the NDB/Connectors.


storage/ndb/include/ndbapi/NdbOperation.hpp:
  Added accessor method to help out the NDB/Connectors.
storage/ndb/include/ndbapi/NdbPool.hpp:
  Fixed header to reflect the implementation.
storage/ndb/include/ndbapi/NdbScanFilter.hpp:
  Added accessor method to help out the NDB/Connectors.
storage/ndb/include/ndbapi/NdbTransaction.hpp:
  Added accessor method to help out the NDB/Connectors.
storage/ndb/src/ndbapi/NdbOperation.cpp:
  Added accessor method to help out the NDB/Connectors.
storage/ndb/src/ndbapi/NdbScanFilter.cpp:
  Added accessor method to help out the NDB/Connectors.