Further work on calc_unit_normal_at_cell_subtriangles, primarily on the docstring examples and also an initial commit for a new function calc_slope_at_cell_subtriangles
Further work on calc_unit_normal_at_cell_subtriangles, primarily on the docstring examples and also an initial commit for a new function calc_slope_at_cell_subtriangles

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