Shapes with class-based targets (sh:targetClass) are not applied to subclass instances

Shapes with class-based targets (sh:targetClass) should target subclass instances. See https://www.w3.org/TR/shacl/#targetClass. Currently it is not the case.
The bug is caused by wrong checks in ValidationProc.getFocusNodes/isFocusNode.
The attached test illustrates the issue.