Cast dataset to ITK float image type
Cast dataset to ITK float image type

Doing so is required because the ITK filter that does Perona-Malik
anisotropic diffusion is templated over float image types only.

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