Enabling multi-threading when computing a series of shortest paths

[pedrocamargo]

Purpose of use
Several uses require the reporting of large numbers of full path trees at once: TNC dispatching, GPS map-matching, Full connectivity tests, etc.

Is your feature request related to a problem? Please describe.
Testing full connectivity on Polaris' networks

Describe the solution you'd like
An object similar to PathResults() but applied to an arbitrary number of ODs

Describe alternatives you've considered
Simple use of Python's threading (considering the release of the GIL by AequilibraE's path computation engine)