Formalize definition of multipath Interactive

[tfpauly]

Get a better/more formal explanation of Interactive mode for multipath based on our experience with Siri, etc.

[tfpauly]

Proposal from Christoph Paasch:

The connection should attempt to minimize the latency for interactive traffic patterns by
transmitting data across multiple paths. The goal of minimizing the latency will be balanced
against the cost fo each of these paths, meaning that depending on the cost of the lower
latency path the scheduling might choose to use a higher latency path. Finally, the
scheduling of the traffic can be done such that data may be transmitted on multiple paths
in parallel to achieve the lowest latency possible.