Started documenting Python bindings

libs/graph/src/python/basic_graph.cpp, libs/graph/src/python/basic_graph.hpp:
  - Allow one to build a graph from anything that looks like a Python list or
    tuple.


[SVN r28324]

libs/graph

@@ -1 +1 @@
-Subproject commit 003e90151ee64e3fcdf75c9698ac7801afb4b1f0
+Subproject commit 631d35bcc2a13e86a8f751d57181e2eb82a23eb7