Merge branch 'pydot' into pydot2

Incorporating changes introduced in networkx#905.

Conflicts:
	networkx/drawing/nx_pydot.py

doc/source/reference/drawing.rst

@@ -51,6 +51,7 @@ Graphviz with pydot
    read_dot
    graphviz_layout
    pydot_layout
+   draw_pydot
 
 
 Graph Layout

doc/source/tutorial/tutorial.rst

@@ -465,5 +465,40 @@ and PyGraphviz, or pydot, are available on your system, you can also use
 >>> nx.draw_graphviz(G)
 >>> nx.write_dot(G,'file.dot')
 
-Details on drawing graphs: :doc:`/reference/drawing`
+Drawing graphs with Pydot/Graphviz
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If `pydot <http://code.google.com/p/pydot/>`_ and 
+`Graphviz <http://www.graphviz.org/>`_ are both installed, then graphs can
+be 1) converted from NetworkX to the pydot format, 2) drawn externally using
+Graphviz, and 3) displayed using the operating system's default graphics 
+viewer. 
+
+The example below constructs a NetworkX graph whose attributes are compatible
+with the Graphviz DOT language and then displays the resulting PNG.  
+Unsupported attributes in NetworkX graphs are silently ignored during the 
+conversion to a pydot graph. Other output formats are also possible. 
+For details, consult the function's docstring and the Graphviz documentation.
+
+>>> G = nx.DiGraph()
+>>> G.graph['rankdir'] = 'LR'
+>>> G.graph['dpi'] = 120
+>>> G.add_cycle(range(4))
+>>> G.add_node(0, color='red', style='filled', fillcolor='pink')
+>>> G.add_node(1, shape='square')
+>>> G.add_edge(0, 1, color='red', style='dashed')
+>>> G.add_edge(3, 3, label='a')
+>>> nx.draw_pydot(G)
+
+If you are working within an IPython Notebook, then this same function can 
+display the graph inline:
+
+>>> nx.draw_pydot(G, show='ipynb')
+
+To make all graphs displayed inline, a global default value can be modified
+(e.g., in the startup file for the profile):
+
+>>> nx.nxParams['pydot_show'] = 'ipynb'
+
+For other details on drawing graphs: :doc:`/reference/drawing`
 

networkx/__init__.py

@@ -50,6 +50,8 @@
 __date__ = release.date
 __version__ = release.version
 
+from networkx.params import nxParams, reset_params
+
 #These are import orderwise
 from networkx.exception import  *
 import networkx.external