ENH: minor improvements for Enum

- found() method for consistency with other classes

- operator()(name, deflt) for similarity to lookupOrDefault,
  but without a dictionary

applications/utilities/preProcessing/mapFieldsPar/mapFieldsPar.C

@@ -229,7 +229,7 @@ int main(int argc, char *argv[])
 
 
     word patchMapMethod;
-    if (meshToMesh::interpolationMethodNames_.hasEnum(mapMethod))
+    if (meshToMesh::interpolationMethodNames_.found(mapMethod))
     {
         // Lookup corresponding AMI method
         meshToMesh::interpolationMethod method =