deleted 3 unreferenced vars in flow_accum
deleted 3 unreferenced vars in flow_accum

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