Add delay between changing values and expensive operation
Add delay between changing values and expensive operation

Reconstructing sample slices is expensive, so add a delay between
changing parameters in the UI and updating the reconstructed slices so
that the user can change the values by more than one at a time.

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