FGM - Added code for approximating the clustering coefficient
Fixed init to include my new function.
Added some tests. Updated style to match PEP-8.
Improved code and added docstrings.
Added proper tests.
Added new function to the documentation.
Use long type for GEXF with Python2 long or Python3 int.
Update line graph code to handle multi(di)graphs and selfloops.
Document that node relabling uses consecutive integers
PEP-8 cleanup
Add 'weight' keyword to Katz centrality
Add 'weight' keyword to eigenvector centrality
PEP-8 updates
Merge pull request #942 from hagberg/relabel-docfix

Relabel docfix
Merge pull request #943 from hagberg/weight-keyword

Weight keyword
Forbid mixing multigraphs and graphs in operators

Users must convert input to matching types before calling.
PEP-8 updates
Deprecate create_degree_sequence.
Add some line (di)graph literature references.
Generate random node indices instead of calling random.choice.