`grouped=true` queries do not return in features

Hello !

From here it says that you can pass a grouped=true parameter to the api request to get the results in the form

> Features
  > Edges

rather than

> Edges

and that works for a request like

/c/en/house?grouped=true

but not for a query like:

/query?node=/c/en/house&grouped=true

my reasoning as to why

It probably comes down to here

conceptnet5/web/conceptnet_web/api.py

Line 74 in 541d4a1

@app.route('/query')

where this route calls query_paginated which then calls FINDER.query here:

conceptnet5/conceptnet5/api.py

Line 244 in 541d4a1

found = FINDER.query(query, limit=limit + 1, offset=offset)

The reason I think this is because FINDER.query has the argument of a single string term argument whereas FINDER.lookup_grouped_by_feature works on a query string that's parsed.

I think it would make sense though to allow lookup_grouped_by_feature to work on a query rather than a single term. This would allow it to be used in most places where grouping is wanted.

I might be missing important a lot of things though so please let me know