- added compile macro NSF_STACKCHECK to provide stack monitoring/debugging (especially useful for multi threaded programs, where stack is more limited)
nsf.c: - added object parameter option "slotinitialize" - renamed object parameter option "invokesetter" -> "slotassign" - call slot.assign instead of setter of object - removed restriction on nosetter/invokesetter: nosetter can be used in connection with slotassign - added regression test for slot.initialize