This moves the documentation out of the constructor, and into the class
definition.

This also changes the semantics of of bin list of size 2, and also
simplifies the histogram code slightly.

This allows easy creation of unfiltered copies of filtered graphs.

Now if a GraphView object is deleted, any property map created for it
reverts its ownership to the base Graph object. This eliminates the
problem of property maps created with transient GraphView objects.

This also fully honors the PYTHON_VERSION environment variable.

This removes some 'undirected' parameters, in favour of graph views.

The default vertex shape is now a circle (not an ellipse), and the
default vertex/edge colors correspond to the Tango palette.

This correctly maintains the edge index metadata.

This fixes a bug where the edge index metadata was not properly copied.

This fixes a leftover bug from the removal of the 'core' submodule.

Now GraphView.base points to the underlying, unfiltered, base graph,
even if "g" is another GraphView instance.

This makes sphinx's autodoc slightly happier.

This implements a GraphView class which allows for convenient,
independent filtering graphs.

Use Palatino as default font, and remove underline from links.