In several issues we run into particular graphviz related issues. These should probably not belong to graph repo perse.

• Allow clients to add more attributes to html output #96
• How to add ports for edges (GraphViz) #92
• Define an abstract record structure clue/graph-uml#23 (related)

What we could do is move this to graph-uml but that library still tries to become graphviz independent.

Maybe graphviz repo is ok? https://packagist.org/search/?q=graphviz has some hits so maybe not the best name.