Resolves #186 and #210

This is a rather large edit because it required a lot of work to track back
to the source line where an opcode came from.  See the comments for
issue #186 for the majority of the explanation.

Issue #210 was solved along with this because the stack trace work I was
doing is what discovered problem #210.
I had the stack trace coming out in backward order.  Fixed it.
With the swapping of the order of the trace, I forgot I also had to
change which of the contiguous same-line calls in the call stack
is the one being printed (the first, not the last):
Added interactive interpreter stack trace ability, and also changed the format of showing filenames and volumes.
(was vol/filename - is now "filename on vol".)
Wo-hoo.  Got it to print the context of flight control updater now too.
review cleanup