grow: Allow m to be configured in growsf_gb
algorithms: Add OslomMerge convenience subclass.
support/algorithms: add get function to get algorithms
grow: GrowFittness: Add support for m>2

Graphs can now be grown with more than two edges per node.
cmty: Add configuration to m>2 edge addition.

- Add different modes for further edge addition: all, all_nonrandom,
  last, last_nonrandom, first.  These control how to make edges
  beyond the second edge.
- Add track_edges feature.  Records the order of edge addition
  for each node.
support/mat	plotlibutil: Make directory if not exists.
util: Add SQLiteDict, simple class for sqlite3 disk dictionaries
cmty: Add some community measure functions.

- cmty_densities, cmty_scaledlinkdensities, cmty_embeddedness,
  cmty_calc, cmty_transitivity.
- These functions could use improvement later, like the networkx
  system of returning values for one community or all.
support/algorithms: Add five new methods

- CliquePerc, SeqCliquePerc, Ganxis, Demon, GreedyCliqueExp
util: _isTrivialType cleanup
grow: GrowFitness: optimize for neighbor set operations
cmty: Update and fix subgraph.

- Fix at least one bug
- Comment it a lot better
- Now supports the shells_overlap mode.  Shells of only overlapping
  communities.
- Add tests/test_cmty2.py with some initial unittest-based tests
util: Remove unneeded fitz.mathutil.Averager imports.
cmty.py: fixed nodeInfo() bug for nodes not assigned to any community
support/algorithms: CliquePerc and SeqCliquePerc layers should zero-pad
cmty: make cmty_graph support overlapping communities.

- Edges entirely contained in an overlap are counted twice.
nxutil: add graphcolor function

This function maps graph nodes to integers in a way that no two
adjacent nodes have the same "color".  It is designed to be fast,
not use the minimum number of colors.
fixup! nxutil: add graphcolor function
support/matplotlibutil: get_axes can take an Axes object directly

- Instead of a filename, you can pass a Axes object and it will return
  it unmodified.  Useful for writing to a pre-existing axes.
support/matplotlibutil: add optional ax_hook, and recursive mkdir