Use the double-secret iPtr->lookupNsPtr field to get post-enter-trace
re-resolutions of commands done in the right context for oo forwards.
added some test cases, based on bug report
merge trunk
[3610404] Re-resolution of command after enter traces invalidate epoch.
Make sure context is such that correct resolution happens.
Add several tests to check consistency of stack traces.
The fix for [3610404] leads to a simplification in the implementation of
forward methods.
Make sure the errors raised by execution traces become errors raised by
the traced command, as documented.  Deletion of the traced command was
supressing that.
Make sure the errors raised by execution traces become errors raised by the
traced command, as documented. Deletion of the traced command was supressing
that.
Testing doing away with the NRRunObjProc routine, which looks like a
useless extra bounce on the NRE trampoline.

Normal testing has no problem with it, but debug-enabled testing
triggers an assert failure.

Either it would be good to have a normal test that fails in the conditions
of the assert failure, or it would be good to discover the assert is
asserting something not actually required, and then make the purge.
Push out a trial patch for more eyes to see.
[3612422]: Refer to correct part of tclvars(n) rather than page itself.
merge trunk
Don't use automatic storage to hold the invocation words of oo::define.
That practice doesn't agree with NRE execution.
Don't allocate memory until you know you're going to use it and arrange for
it to be freed.  Leak!
Tidy the code and add a test.
[8ff0cb9fe1] Make Tcl_NREvalObj() (and friends) behave as documented, by
only scheduling evaluation and not doing any of it until the caller routine
returns.  This fixes some serious errors in [coroutine] too.
Correction to documentation
More coroutine tests.
Remove assertion that is not true in some circumstances (--enable-dtrace).
Make Dispatch() the single point for calling a Tcl_ObjCmdProc, and attach
the DTRACE machinery there (one place, not two).