Use @require and other decorators to simplify code imports/checking
Return matrix instead of array for laplacian functions
Whitespace cleanup and formatting
Refector conditional so there is only one return
Fix katz centrality doctest formatting
Fix core tests

Adjust test graph to map nodes since the new havel hakimi algorithm generates different node ordering
Merge pull request #876 from hagberg/core-tests

Fix core tests
Merge pull request #877 from hagberg/katz-test

Fix katz centrality doctest formatting
Merge pull request #833 from hagberg/laplaican-matrix

Laplaican matrix functions should return matrix
Fix import error and typos in scc tests
Remove failing threshold graph test

Need to rework for matrix type return from laplacian_matrix
Merge pull request #882 from hagberg/threshold-test

Threshold test
single_source_dijkstra_path passes cutoff
Merge pull request #883 from tdihp/patch-2

single_source_dijkstra_path passes cutoff