Minor changes to DataSource to undo tilt angles workarounds
Minor changes to DataSource to undo tilt angles workarounds

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