pareto does not work if targets are provided

The -p and -pf options gives nothing if used with targets (-t option):

```
python -m predator networks/ns_2.sbml -pf -t A
DEBUG args = Namespace(export=None, forbidden_seeds=[], forbidden_seeds_file=None, greedy=False, infile='networks/ns_2.sbml', info=False, intersection=False, no_prerun=False, no_topological_injection=False, pareto=False, pareto_full=True, scc_with_asp=False, seeds=[], seeds_file=None, semantic_injection=False, targets=['A'], targets_are_forbidden=False, targets_file=None, union=False, verbose=False, visualize=None, visualize_dag=None, visualize_without_reactions=None)
end of solutions.
Rendering…
-> Ok!
TIME DATA EXTRACTION: 0.001s
TIME PRE-RUN : 0.315s
TIME SCCs EXTRACTION: unperformed
TIME SEED SEARCH : 0.001s
TIME RENDERING : 0.0s
TIME TOTAL : 0.002s
```