Returning both nodes and paths adds unnecessary convoluted code in the
client and server code. In addition, the global 'visit/' endpoint is not
listed in any of our use-case, and having the two separate sub-endpoints
(visit/nodes and visit/paths) is enough.

Note: the server code was not fully updated after recent code clean up, so the
visit/ global endpoint needed: a new function on its own (repeating again the
code in visitNodes and visitPaths) and a custom class for the JSON output
format.