NamedGraph and presentations

[slwu89]

Hi @epatters, as part of thinking about more comprehensive visualizations for the queries making up data migrations I have discovered that Catlab defines a NamedGraph type here (https://github.com/AlgebraicJulia/Catlab.jl/blob/main/src/graphs/BasicGraphs.jl#L593) but as far as I can tell it is not used anywhere, and the docstring remarks that it can represent the graph corresponding to a presentation of a FinCat.

Likewise in the graphviz integration, we have this function https://github.com/AlgebraicJulia/Catlab.jl/blob/main/src/graphics/GraphvizCategories.jl#L16 that takes a Presentation and visualizes it.

I propose that we make graphviz support for NamedGraph objects, and a new function to generate a NamedGraph from a Presentation (what should it be called?) and simplify the to_graphviz_property_graph for presentations. What do you think of this plan? I'm happy to work on it if you think it is a good idea.

[slwu89]

Closing this, as to_graphviz already works for NamedGraph objects, didn't spend enough time looking around.

[epatters]

Great, I love to hear it :)