This fixes the expected values for several doctests, after
random_graph() re-factoring.

This implements a shortest_path() function which returns the shortest
path between two vertices.

This also modifies shortest_distances, such that a predecessor map is
optionally returned.

Support for edge/vertex labelling is 99% done, but it is currently
impractical to compile with GCC. If GCC 4.5 doesn't do a better job,
then a workaround would be necessary.

This is a wrapper around BGL's boyer_myrvold_planarity_test.

This includes the shortest_distance() function in the topology module.

This completes all the documentation up to this point.

This modified several docstrings and introduces a quick-start guide.

Reduce duplication of code for loading C++ modules.

This also creates the misc sub-module. This may be re-organized in the
future.

Also, get rid of g.underlying_graph(), and rely on "private" variable
g._Graph__graph instead.

The whole histogram code has been redone, and the code has been
simplified. The three-point vertex-edge-vertex correlation has been
scrapped, since it's not frequently used, and would make compilation
even more expensive.

This also adds some missing files to the generation routine.