Adding code by A. Kiryunin

This is to add some jO and macros to compute HEC sampling fractions, developed by @kiryunin . Tagging @jchapman and @mduehrss .

Database/AthenaPOOL/AthenaPoolCnvSvc/src/AthenaPoolCnvSvc.cxx

@@ -542,7 +542,7 @@ StatusCode AthenaPoolCnvSvc::commitOutput(const std::string& outputConnectionSpe
          return(StatusCode::RECOVERABLE);
       }
    } else if (currentFileSize > m_domainMaxFileSize) {
-      ATH_MSG_WARNING("FileSize > MaxFileSize for " << m_outputConnectionSpec);
+      ATH_MSG_WARNING("FileSize > domMaxFileSize for " << m_outputConnectionSpec);
       return(StatusCode::RECOVERABLE);
    }
    // For "safety" we reset the output file and the technology type