Add support for graph database formats

[buger]

When program becomes too complex viewing it via SVG or image becomes problematic.
However if will be possible fit it to some graph database, it will alow dynamically querying your code, for example with https://www.nebula-graph.io

So basically exporting this data in RDF or JSON-D. (RDF is more common).

[ondrajz]

Hey, thanks for raising this issue! This use-case is valuable and is definitely something I am currently exploring.