PCE analysis of GNPY results

Impairment aware Path calculation: a check of optical feasibility is needed during path validation/selection. The code to process results provided by the external PSE (GNPY) tool is developed.

Develop the code to provide GNPy with initial constraints when the path analyzed is not feasible. After GNPy has computed a new path for the PCE, this last shall check using the include constraints that the new path is valid from a pure graph standpoint.