- fixed handling of TclNRRunCallbacks, such that coroutines can be easily used (more testing required) - added temporary routine ::nsf::yieldcheck for coro debugging - renamed Tcl85showStack() to TclShowStack()
- fixed a crash for tcl 8.6b1 in return value checking. now it complains about missing cmdPtr; it is not clear, why this is missing at the first place in 8.6b1 while working in 8.5