Add Cylinder to predefined node shapes #49
Description
Hello Ivan,
I'm one of the happy users of your package and I'm very satisfied with its functionality. But today I wanted to use cylinder node shape (listed in graphviz docs about shapes), but the latest version of this library doesn't declare cylinder in Shape. Would be willing to add it / open to PR from me adding it? At the moment I have to work around the lack of Cylinder constructor by doing something like this: customAttribute "shape" "cylinder"..