Added handling of multi-element parameters
Added handling of multi-element parameters

After collecting all the parameter values from the UI widgets, make a
pass through the map entries and merge individual parameter element
map entries into a single entry where the key is the parameter name
and the value is a QList of QVariants, one for each element.

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