Constraint specified in where clause is not parsed

[wouterwln]

Is directly stored but is not parsed like constraints in constraint macro is parsed.

[wouterwln]

@bvdmitri we might not even implement this, I think it's a significant burden to make with little benefit

[bvdmitri]

We might not implement this at this stage, lets keep this open and see if we actually need it in the future. If no-one complains, we will close the issue.

[wouterwln]

@bvdmitri let's close? I think GraphPPL.default_constraints covers this particular use case