Add graphviz generation and visualization

This requires graphviz to be installed on your machine. If you run the
command with sudo, it will create the files with the original user
ownership to make it easier to remove them without root.

types.go

@@ -26,6 +26,7 @@ import (
 type Type interface {
 	Init()
 	GetName() string // can't be named "Name()" because of struct field
+	GetType() string
 	Watch()
 	StateOK() bool // TODO: can we rename this to something better?
 	Apply() bool
@@ -71,6 +72,10 @@ func (obj *BaseType) GetName() string {
 	return obj.Name
 }
 
+func (obj *BaseType) GetType() string {
+	return "Base"
+}
+
 func (obj *BaseType) GetVertex() *Vertex {
 	return obj.vertex
 }
@@ -198,6 +203,10 @@ func (obj *BaseType) Process(typ Type) {
 
 }
 
+func (obj *NoopType) GetType() string {
+	return "Noop"
+}
+
 func (obj *NoopType) Watch() {
 	//vertex := obj.vertex // stored with SetVertex
 	var send = false // send event?