Reduce Arcing

[ljedrz]

Many objects in the Router contain numerous Arcs to allow cloning; however, those objects are never cloned individually (only as part of the entire Router), so there is no need for those Arcs to be so fine-grained.

This PR removes all the internal Arcs under Router, and wraps the Router itself in an Arc; this will greatly reduce the number of atomic operations done during each call to Router::{connect, disconnect} and any other future operation that requires the Router to be cloned.