Add query language alternatives?

[pyroscope]

Add more query language options? Possibly via a new rtquery command, to not blow up rtcontrol further.

• https://github.com/openstack/yaql
• https://github.com/timtadh/pyflwor
• https://github.com/adriank/ObjectPath
• GraphQL

Output result as hashes or into a view. Give rtcontrol a --from-hashes ‹file› option to read a query result from a list of hashes (- = stdin).