Use vtkIdType rather than unsigned in for indexing data
Use vtkIdType rather than unsigned in for indexing data

Large datasets will break this... Preemptive fix.

cjh1/tomviz,thewtex/tomviz,mathturtle/tomviz,OpenChemistry/tomviz,thewtex/tomviz,mathturtle/tomviz,cryos/tomviz,cryos/tomviz,cjh1/tomviz,OpenChemistry/tomviz,cjh1/tomviz,mathturtle/tomviz,cryos/tomviz,OpenChemistry/tomviz,thewtex/tomviz,OpenChemistry/tomviz