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

[kinetic]
category=kinetic

[functionality]
category=functionality

[installation]
category=installation

[efficiency]
category=efficiency