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
#ifndef __PYTHON_STATIC_PERSISTENCE_H__
#define __PYTHON_STATIC_PERSISTENCE_H__
#include <topology/static-persistence.h>
typedef StaticPersistence<> SPersistence;
typedef SPersistence::OrderElement SPersistenceNode;
typedef SPersistence::OrderIndex SPersistenceIndex;
#endif