#22 File copying waits for all copies to finish

[Benjamin Sprague]

Because of how tkwait stacks recursively, runs don't
start until after all of the copying runs have finished
copying (even if one of them finishes way before the
others, it waits for the others to finish). However, if
the last run to start copying finishes first, it will
go before the others do. This is because tkwait won't
return until it and all of the tkwaits called during
it's run have completed. So I have to come up with some
better code in simNode than this:

tkwait variable ${cpyVar}(finished)