automatic graph construction

[msurkovsky]

I did a first version of automatic construction of graphs from structure. I'd be glad for any feedback, is it a right way or do you have any other idea how to extract information and what to specify? Tomorrow I'm going to prepare more examples of usage and try to use Graph from the lib instead of ours.

Here is a very simple example:

import haydi as hd
from haydi.ext.graphsrenderer import InstGraphRenderer

nodes = hd.Range(3)
edges = nodes * nodes

g = edges.filter(lambda (x, y): x != y).run()
gr = InstGraphRenderer(g)
# gr = gr.nodes(nodes.run()) # if not used automatic identification of nodes is proceed

G  = gr.assemble_graph()

G.write("test.dot")

[msurkovsky]

I consider the pull request as final from my side :).