Denormalise related resources

[ddeboer]

Currently this module leaves out related resources (Zotonic includes their titles to find resources by their relations). Using the pivot templates in Zotonic 1.0, we can include them again. Remember that we already have the elasticsearch_put notification for really customised inclusion of related resource terms.

[fredpook]

I am working on adding (at least) the titles of keywords to the rsc/doc index.
This for improving the autocomplete functionality (issue #12)

Do you want me to add this in this module or shall I add it in my project?

[ddeboer]

You can add it to this module: it should probably be scoped to suggestions.

We don’t need to add related resources for match_objects, because that already works purely with the incoming|outgoing_edges that we already have.