Test with branching

Trying my hand on branching
Revert "Test with branching"

This reverts commit 9c14122a7687cd398f8d0ba7960bd0b7c139e08a.
Rectified Priestly Taylor method for calculating PET

corrected Priestly Taylor method for calculating potential
evapotranspiration. This is the first edit. Future commits will try to
include documentation.
Minor changes

minor updates to radiation and soil moisture components
nothing to commit

Git is asking me to commit changes, even though I have no changes.  Not
sure what is going on.
Merge branch 'master' of https://github.com/landlab/landlab

Conflicts:
	README.md
	docs/install.rst
	docs/landlab.components.radiation.rst
	docs/manual_index_alt_format.rst
	docs/model_grid.rst
	landlab/components/radiation/radiation_field.py
	landlab/components/soil_moisture/SM_spatial_DEM_PET.py

landlab/components/soil_moisture/examples/soil_moisture_field_example.py
	landlab/components/soil_moisture/soil_moisture_field.py
	landlab/grid/base.py
	landlab/grid/hex.py
	landlab/grid/radial.py
	landlab/grid/raster.py
	landlab/grid/raster_funcs.py
	landlab/grid/tests/test_raster_funcs/test_node_id_of_adjacent.py
	landlab/grid/voronoi.py
	landlab/utils/structured_grid.py
	setup.py
Minor change to link_ca test case
Fixed conflicts.
Fixed conflicts.
Update raster.py

trying to get rid of my mistakes, but still not done
Fixed conflicts.
Fixed conflicts.
Fixed some of the conflicts.
Update base.py

Nicole undoing her mess.
Update hex.py

Nicole undoing her mistakes
Update radial.py

Nicole undoing her mistakes
Update raster_funcs.py

Nicole undoing her mistakes
Update test_node_id_of_adjacent.py

Nicole fixing mistakes
Update voronoi.py

Nicole fixing her mistakes
Update structured_grid.py

Nicole fixing her mistakes