Skip initial deep copy of input data
Skip initial deep copy of input data

The deep copy wasn't really necessary.

In addition, mark that an Operator has a child data source in
createNewChildDataSource().

OpenChemistry/tomviz,OpenChemistry/tomviz,mathturtle/tomviz,mathturtle/tomviz,OpenChemistry/tomviz,mathturtle/tomviz,OpenChemistry/tomviz