----
- Added ``ObjectGraph.edgeData`` to retrieve the edge data
from a specific edge.
- Added ``AltGraph.update_edge_data`` and ``ObjectGraph.updateEdgeData``
to update the data associated with a graph edge.
altgraph is a fork of graphlib: a graph (network) package for constructing
graphs, BFS and DFS traversals, topological sort, shortest paths, etc. with
graphviz output.