Cleaned up calculate_slope_aspect_at_nodes_bestFitPlane.
Cleaned up calculate_slope_aspect_at_nodes_bestFitPlane.

Minor cleaning and renamed: calculate_slope_aspect_at_nodes_bestFitPlane to
calculate_slope_aspect_at_nodes_best_fit_plane.

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