Changes in Python Bindings:
* the exposed C++ simplex has Empty data
* Python Simplex constructor with data as well as data-based
comparison functions are implemented in pure Python
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)