nsf.c: - Reform of subclass/superclass handling. * unifying transitive subclass handling * localizing and documenting caching of subclass/superclass lists * eliminating repetitious computation of subclass lists * refactored code, renamed some functions to better refelect their purpose * improved documentation - fixed a potential crash for class deletion triggering implicit deletions further deletions referencing the parent class - extended regression test
- Avoid duplicate entries in instance lists for diamond inheritance by maintaining the set of already processed entries in NsfClassInfoInstancesMethod1() and GetAllInstances(). - extended regression test - removed "namespace import" in objectsystem test