Modify sink_filler in line with lake_mapper
Modify sink_filler in line with lake_mapper

Minor under-the-hood changes needed to maintain compatibility; class
name change.

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