Set attributes for all nodes and edges

[marcelom97]

Is there a way to set global attributes for nodes and edges?

I want to do something like this

digraph G {
  node [style = filled];
  edge [color = "red"];

  ...
}

[marcelom97]

I found that you can set them using Graph.Attr method https://github.com/goccy/go-graphviz/blob/master/cgraph/cgraph.go#L1127

The first argument of type int is to specify if you want to apply the attributes to graph, node or edge

I suggest to define the kind as a new type

ex:

type Kind int

const (
	KindGraph Kind = iota
	KindNode
	KindEdge
)

Also add documentation to Graph.Attr