hierarchical treebank data

[gregorycrane]

To illustrate a layered, hierarchical approach.

default: SpaCy Grecy output
better: Glaux 2.0
best available: https://github.com/gregorycrane/Daphne/tree/master/data

We will also need to think about how to represent alternate authoritative treebanks. We should have an idea of how to represent them now as we think through the front end.