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
set (targets
triangle
triangle-zigzag)
set (libraries ${libraries} ${Boost_SERIALIZATION_LIBRARY})
foreach (t ${targets})
add_executable (${t} ${t}.cpp)
target_link_libraries (${t} ${libraries})
endforeach (t ${targets})