Grlp

1. New support by fmcnab towards generating, plotting, and analyzing river networks
a. Improved function for plotting schematic network planforms, avoiding overlapping segments and using space more efficiently
b. Functions to fit, for a given network, a Hack-style power law for discharge (rather than upstream drainage area) as a function of distance downstream
c. Improved/additional calculation of network metrics (e.g. Horton's ratios)
2. Jupyter notebook towards Landlab integration (in progress) by jeffskwang and niscen

McNab (2022, submitted) linearization examples and plotting scripts

Code for metrics based off of a linearized form of the main equation, including the following responses to a periodic forcing:
* Gain
* Lag
* Diffusivity
* Equilibration time
and more

* Synthetic network builder and general network tools from fmcnab
* Jupyter notebook (1D profile) from ericbarefoot
* README documentation and Python 2+3 support in example from awickert

Check package availability in Firefox after uploading to PyPI

* Added helper shell scripts to publish code with PyPI: goal to keep these in synch from this point onwards.

In addition, includes the v1.3.1 updates, which on further review add functionality in a way that is more in line with a "minor" update than a "patch" update. Copy/pasting these here:
* Compute width and depth with the aid of grain-size information (optional)
* Update some examples (Python 3; core code updates)
* Directionality to S0
* Test variable gravel inputs and attrition in `test_uplift_equals_qs.py`