Speed issue with Region Aware

[peterrrock2]

This was an issue noted by @proebsting. It appears that regions-aware frcw and regular frcw have some pretty serious time discrepancies arising from the way that the region weights are implemented. More precisely, it appears that when running a vanilla run of frcw against a run with region surcharge 0, the surcharged version appears to operate somewhere around 3x slower. It would be good to rethink how the region surcharges are stored and accessed.

Note for development: probably the best way to deal with this would be to store the total surcharged weight as an edge attribute with a default value of 0.