nondominated sorting in C

[jakobbossek]

Just commited a first version. Significant performance improvement as expected. However, some issue need to be solved and code can be optimized as well.

• currently we check for each i, j twice if i dominates j or vice verca. We need to save this relations.
• we need to return the domcounter as well (just copy after generation since the original is modified in place during the sorting procedure)
• stack imbalance issue: at the moment two vars are protected (rank and domcounter), but the latter is not returned/unprotected.