My entire goal for this is to improve script authoring.  Back when
Greasemonkey was new, all users were script authors.  I believe that no
small reason for why it took off is because working with a Greasemonkey
script is so easy: Just edit the file and reload the page.  Bam.  I
think this is _really_ important.

But today, if you want to add an @require or @resource, this isn't
enough.  If you want to change the description or the name, a reinstall
(at least) is required.  It's clunky, especially when all that
information is already right there in the script metadata.  It's a poor
system where the author has to know "you can edit this part of the file
and it works, but changing that other part, which is really important
when the script is installed, has no effect".  And the workarounds.

But as mentioned, the cost of developing a backwards compatible
solution, given (at least a bit of) my time invested in trying to make
it happen, seems infeasible.  Part of the cost is merging the @includes
that are, now for installed scripts, stored in config.xml, those stored
in the file, and not losing data.

I plan to spend a while thinking out possibly non-backwards-compatible
options, and how drastic their impact might be.