It's very useful to be able to pass parameters to tests.
Unfortunately, our previous --test argument syntax didn't
permit it, because , was used as a delimiter for multiple
tests. With this change, we change , to become a delimiter
for arguments, as it is with other options to mn. For now,
we introduce + as a separator, as it is legal in filenames
and therefore shouldn't conflict with special characters
used by Unix shells.
We also reorganize mn a bit to make it hopefully slightly
clearer.
Bob Lantz
7e5324c80e