Add support for a scalar range node type

This would allow the count-model to be more readable, which will make generating collections of the right size easier.

Proposed format:
```clojure
{:type :range
:min 1 ; inclusive, optional
:max 3 ; inclusive, optional
:inf -5.0 ; exclusive, optional
:sup 5.0 ; exclusive, optional
}
```

`:min` and `:inf` cannot appear at the same time in the node,
`:max` and `:sup` cannot appear at the same time in the node.