Include resource types.
Add subgraphs for Parameters and Outputs.
Add support for references in Outputs.
Add edges for 'Fn::GetAdd' references.
Refactor graph rendering to unify main graph and subgraphs.
Clean up display of nodes without details.
Slightly less ugly way of setting up variables for subgraphs.
Add labels to whole graph, and output and parameter subgraphs.
Add some missing semicolons.