test/graph_test.cc added.
It discovered several bugs and warnings in 'include/smart_graph.h',
in 'include/skeletons/graph.h' and in 'work/alpar/list_graph.h'.
They have also been fixed.
1 ./preflow_demo_leda < $1
2 ./preflow_demo_boost < $1
3 ./preflow_demo_jacint < $1
4 ./preflow_demo_athos < $1
5 ./edmonds_karp_demo < $1
6 ./edmonds_karp_demo_alpar < $1
7 ./edmonds_karp_demo_boost < $1