Move Graphviz to own repo?

[clemens-tolboom]

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.

[clue]

Indeed, this issue has been raised several times already.

I'm not opposed against this at all. Unless anybody can find a reason to not split this off into a separate repository, I'll add this to my TODOs.

The other graphviz packages have a somewhat different focus, so it makes sense to keep this as a separate repository which is associated to this graph library as its core.

[clue]

Graphviz will eventually be split off to graphp/graphviz, see also the linked ticket graphp/graphviz#1.

[clue]

Also GraphViz is the only component that takes advantage of this Layoutable class, so it will be removed from this repository as well. Instead, ticket #100 will eventually add a general purpose collection of properties, which can also include GraphViz layout attributes, so eventually we can drop the whole Layoutable class.

Because of this, this ticket is blocked until #100 is addressed. Any input is welcome.

[clue]

Ticket #100 has been resolved via #103, we can now split this off.

[clue]

The new repository depends on #103, so we should tag a v0.8.0 release before splitting this off. As such, this ticket will be moved to the v0.9.0 milestone.

NVM, GraphViz will be removed via #115, the separate package currently targets this master branch and will be updated immediately after to target the v0.8.0 release.