Move firstRow designation from subgroup to group
Move firstRow designation from subgroup to group

- Issue MatterHackers/MCCentral#3127
Missing slice setting row borders after first/last row modifications

jlewin/MatterControl,mmoening/MatterControl,mmoening/MatterControl,larsbrubaker/MatterControl,mmoening/MatterControl,jlewin/MatterControl,jlewin/MatterControl,unlimitedbacon/MatterControl,unlimitedbacon/MatterControl,larsbrubaker/MatterControl,larsbrubaker/MatterControl,unlimitedbacon/MatterControl,jlewin/MatterControl,larsbrubaker/MatterControl,unlimitedbacon/MatterControl