add net flux and flux div for faces and nodes
add net flux and flux div for faces and nodes

csherwood-usgs/landlab,ManuSchmi88/landlab,Carralex/landlab,Carralex/landlab,laijingtao/landlab,SiccarPoint/landlab,amandersillinois/landlab,cmshobe/landlab,Carralex/landlab,ManuSchmi88/landlab,cmshobe/landlab,laijingtao/landlab,csherwood-usgs/landlab,landlab/landlab,SiccarPoint/landlab,RondaStrauch/landlab,RondaStrauch/landlab,cmshobe/landlab,RondaStrauch/landlab,ManuSchmi88/landlab,landlab/landlab,landlab/landlab,amandersillinois/landlab