Removed the points iterator in PersistenceDaigram; replaced it with a __iter__ method. Got rid of some python code in __init__.py, since it was not needed with the above change. Changed the docs to reflect this.

#include "birthid.h"
#include "optional.h"

namespace dp = dionysus::python;

void export_birthid()
{
    python_optional<dp::BirthID>();   
}