refs #568, improved error handling / parameter names in readers

* better categories
* parameter name as static functions
* error message in structure CDatabaseReader::JsonDatastoreResponse
* prefixed members of structure with _m
* consolidate severity

src/blackmisc/network/entityflags.cpp

@@ -77,7 +77,7 @@ namespace BlackMisc
             case StartRead:
                 return CStatusMessage::SeverityInfo;
             case ReadFailed:
-                return CStatusMessage::SeverityWarning;
+                return CStatusMessage::SeverityError;
             default:
                 Q_ASSERT_X(false, Q_FUNC_INFO, "Missing state");
                 return CStatusMessage::SeverityInfo;