deal with transitivity

[kohlhase]

This issue is to start a discussion.

We should have a setting that computes the transitive skeleton of a graph and only show that.

I thought that the JSON sources should only generate transitive skeletons, but I think we should reconsider.

I now think that there should functionality in the TGView client that (like showing/hiding meta edges) show/hide transitively redundant edges: sometimes we want to see the full set of edges and sometimes we do not (to avoid clutter).

For this we might have to annotate edges in the JSON with properties (here whether an edge belongs to a transitive relation).

[kohlhase]

BTW, the same holds for other properties of relations. E.g. reflexivity symmetry, ...

All in all this would make TGView more "semantic".