add progress bar to weighted back projection
add progress bar to weighted back projection

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