Log Message:
py-networkx: updated to 2.3

Announcement: NetworkX 2.3
==========================
We're happy to announce the release of NetworkX 2.3!
NetworkX is a Python package for the creation, manipulation, and study of the
structure, dynamics, and functions of complex networks.

For more information, please visit our website <http://networkx.github.io/>_
and our gallery of examples
<https://networkx.github.io/documentation/latest/auto_examples/index.html>_.
Please send comments and questions to the networkx-discuss mailing list
<http://groups.google.com/group/networkx-discuss>_.

Highlights
----------
This release is the result of 6 months of work with over 92 pull requests by
30 contributors. Highlights include:

- Dropped support for Python 2. We are no longer supporting Python 2.7 and we will
  start changing code to take advantage of Python 3 features we couldn't before.
- Added some Moral Graph analysis functions.
- Enable matplotlib drawing using curved arrows via connectionstyle parameter.
- Remove ticks and axes labels from matplotlib plots.
- Two new generators of Harary Graphs.
- Added Dual Barabasi-Albert model
- Added VoteRank algorithm
- Added Equitable coloring algorithms
- Added planar layout algorithms
- Les Miserables network example
- Javascript example update

Improvements
------------
- Change default colors to be color-blind friendly
- Many bug fixes and documentation improvements
- Speed up of simple_cycles
- Improvements for reading various formats like GML, GEXF, Graphml
- Allow subclassing to access node_attr_dict_factory

API Changes
-----------
- The G.fresh_copy() mechanism for creating an empty_graph of the same
  type (introduced in v2.0) does not playing nicely with pickle and others.
  So, we have removed the code that caused a need for that. Instead you
  should use the more natural G.__class__() syntax to get an empty_graph
  of the same type as G.

Deprecations
------------
- The Graph.fresh_copy() method should now use Graph.__class__()
- ReverseView class removed in favor of reverse_view() function.