No Pareto-fronts for CTP-problems

Hi,
When I try to get the Pareto front for CTP1-8 problems, None returns.
In ctp.py there are lines like these:

```python
def _calc_pareto_front(self):
    return load_pareto_front_from_file("ctp1.pf")
```

But there are no files with names like "ctp*.pf".