Added code to expose the persistence_diagram class, the bottleneck_distance function and the point class to python. Most of the commonly used methods for each class have been exported. The constructor for point now requires that a data argument be provided along with x and y coord. This needs to be made optional. The constructor for persistence_diagram could possibly be rewritten as well.

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

namespace dp = dionysus::python;

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