Add Scala API
- Based on the Java API except it uses scala data structures (e.g.
Seq/Map/Node/Enumerations) and changes for scala specific code
snippts/documentation
- Modify Java API to match Scala API as close as possible so that
looking at the differences is easier. For example, even though
private[japi] is ignored in the Java API docs, still add it so the
diferences are clear.
- Copy tests from daffodil-japi but changed to use the scala API.
