Finish full support of "reusable" field sets

[webmat]

#155 describes what's actually a more widespread problem. Currently, schema.csv and template.json don't include any mention of the reusable field sets in their expected locations. Example: source has no mention of geo, which can be nested at source.geo.

We need to update the generator to do so. The discussion on whether we can accomplish that with path matching for ES specifically is another matter, tracked in #155.

The goal here is to have each generated file be correct and list every field, including reusable ones.

[webmat]

Solved by #336