void clear() {
            partChanges.clear();
            neighborChanges.clear();
            neighborChangeSources.clear();
            count = 0;
            recalcs = 0;
            lastCaller = null;
            reusableRuns.add(this);
        }
Used when the propagator did not change signal, but a new connection may
have been established and signal needs recalculating
core/src/main/java/mrtjp/projectred/core/RedstonePropagator.java