Log Message:
py-networkx: updated to 2.1

NetworkX 2.1

Highlights
This release is the result of four months of work with 75 pull requests by
37 contributors. Highlights include:

  - Arrows for drawing DiGraph edges are vastly improved!
    And an example to show them.

  - More than 12 new functions for graph generation, manipulation and/or
    new graph algorithms.

    - Add a large clique size heuristic function
    - Add rooted product function
    - Label Propagation Community Detection
    - Minimum cycle basis
    - Add Mycielski Operator
    - Adds prefix_tree, dag_to_branching, and example.
    - Add inverse_line_graph generator
    - Steiner tree and metric closure.
    - Add flow based node and edge disjoint paths.
    - Update geometric networks with new models
    - Graph edit distance
    - Added function for finding a k-edge-augmentation

  - G.name is no longer processed by graph operators. It remains as a
    property mechanism to access ``G.graph['name']`` but the user is in
    charge of updating or changing it for copies, subgraphs, unions and
    other graph operations.

Improvements
  - Many bug fixes, documentation changes.
  - Speed improvements especially for subgraphs.
  - Changed input variable names for functions using ``**kwds``
    to avoid name collisions -- especially ``add_node``
  - New examples for arrows and spectral embedding of the grid graph.