adding dispersion as a centrality measure
updated dispersion to use built in nx methods and set comprehension
incorporating dschult set method suggestions... with significant increase in speed
refactored to allow optional u, v... added suggestions for normalizations...
Addresses #1048.
Node labels must be within double quotes. Addresses #1048.

Tuple labels are now converted to strings:
   (1,2) -->  "(1,2)"
Add omitted quote=True option to escape(). #1048.
Add unit test for #1048.
good thing we do tests
clean .gitignore and tests bug
correcting dict comprehension in tests....
ENH: add reverse kwarg for topo sort
GML read/write with numeric HTML entities. #1061
MAINT: use reverse=True for some topological_sort calls
Merge pull request #1048 from chebee7i/gmlbug

Better .gml handling. Fixes #1048. Fixes #1061.
"fixing docstring"
Fixes #1063.
Merge pull request #1064 from chebee7i/gmlbug

Fixes #1063.
Merge branch 'master' into dispersion
Remove unused math directive in docstring.