BGL: Revise cost_recorder event visitor

[marip8]

The cost_recorder event visitor makes a copy of the edge weight property map every time it is utilized in order to get the cost of an edge. It seems like there should be a more efficient way of getting the edge weight that avoids this unnecessary amount of copying

descartes_light/descartes_light/solvers/include/descartes_light/solvers/bgl/impl/event_visitors.hpp

Line 63 in d56038b

auto edge_weight_map = boost::get(boost::edge_weight, g);

Also, the class should probably be renamed to distance_recorder since it is actually recording the distance from the start vertex to each visited vertex