Major change: 'benchmark_t' class now accepts as input a 'graph_generator_t' object that define a policy for generating graphs in the runs of a benchmark (e.g., either generated different graphs in each run or use the same over all runs).

Bug fix: in the 'check_graph()' function, don't assume that triples in graph edge '(r,c)' and the specular triples in graph edge '(c,r)' are arranged in the same order (e.g., '(r,c)[k].dist == -(c,r)[k].dist') since some algorithms (e.g., Floyd-Warshall) sort triples in the edges by their distance, thus invalidating that assumption. To fix that, we now perform a scan of specular triples in '(c,r)'.

Fixed a problem with std::getline(). Added concept of working graph and the possibility to use as working graph either the input graph or the minimal graph. Added menu options to save/show either the input graph or the working graph. Added interval-interval structural query option

[new] Test: added test program to propagate constraints in a minimal network multiple times (useful to study convergence properties)

[change] UI console: added removal of constraints; improved the UI for changing graphs; added the option to use the minimal network as input graph

[change] UI console: added removal of constraints; improved the UI for changing graphs; added the option to use the minimal network as input graph