Cleaned up Python bindings to restore functionality:
* StaticPersistence is iterable, its nodes are usable (sign, pair, cycle)
* StaticPersistence knows how to map its nodes into Filtration indices
* moved PythonCmp into utils.h
* minor cosmetic changes
add_subdirectory (alphashapes)
#add_subdirectory (ar-vineyard)
add_subdirectory (cech-complex)
add_subdirectory (consistency)
add_subdirectory (cohomology)
add_subdirectory (fitness)
#add_subdirectory (grid)
add_subdirectory (triangle)
add_subdirectory (poincare)
add_subdirectory (rips)