Tim Martin authored Aug 06, 2020 and Frank Winklmeier committed Aug 06, 2020

 * Introduce new small transient DAG class.
 * Populate DAG on call to features, filtered on the chain(s) and other options
 * Change feture-grabbing to use this filtered sub-graph DAG
 * Include early-escape efficincies in this subsiquent navigation.
 * Aim to save substantial CPU in events with significant branching-merging-branching.
     * Both in sub-graph construction (instead of locating all linear routes).
     * And in sub-graph navigation (only explore from each node once)