`getGraphVal()` is missing from the Solution object.

[dimitri-justeau]

trafficstars

From a Solution object, we can retrieve the value of an IntVar, a SetVar, or a RealVar. But this is not possible for a GraphVar. I believe that we "forgot" to integrate this when we migrated choco-graph into choco-solver.

It should not be difficult to allow this, I can take time to do it.

Cheers,

Dimitri