Add hidden options to show the graphs in the utility.
Add a preliminary implementation of the hawick_circuits algorithm.
Add the vertex_to_edge_path functor.
Add the graph_test_base utility class.
Add the as_cycle_visitor class.
Refactor graph_cycles_test.hpp so it uses graph_test_base.
Modify the cycle algorithms in several ways:
  - The algorithms now only work on vertices. To transform vertex
    paths to edge paths, use the vertex_to_edge_path wrapper.

  - The graph_cycles_test was adjusted to reflect those changes.

  - The analysis transforms vertex paths to edge paths by itself, so
    it will be simpler to swap cycle detection algorithms if needed.

  - Because the multidigraph_all_cycles algorithm was only a wrapper
    over tiernan_all_cycles, it was removed.
Add the hawick_unique_circuits algorithm.