added capability to disable edges

this commit adds the capability to disable certain edges, so that pathfinding-algorithms do not consider the edge until it is activated again. One possible usecase may be with pathfinding in road-networks where construction-sites can make pathes unusable. the current implementation may not be optimal, but since the generic parameter for the edge-classes is not constrained, which would allow to add an 'isActive'-Method in IntrusiveEdge, I have not found a better solution. I understand that in the current architecture, a constraint for the edge-classes would limit the featureset, so constrainig may not be an option.