Disambiguate the meanings of the VoltXML name "type".
Disambiguate the 2 meanings of the VoltXML name "id".
Disambiguate the meanings of the VoltXML name "operation", distinguish: "aggregation", "orderby", and "simplecolumn". Drop unused "bool"
Merge pull request #350 from VoltDB/ENG-3752-precursor

3 commits, each clarifying the usage of a different getVoltXML element name.