Make explicit the requirement that Works which Use the Received Work are licensed
under copyleft-next if you distribute them.

Remarks:
1) The definition of CS already covers WU. That's exactly what I felt it was missing,
when I said the current copyleft-next seems to be a 'weak copyleft'. Because:
- CorpX receives LibreOffice math library under copyleft-next (libA)
- CorpX uses the library in their libB. libB builds an UI for math functions from libA.
- CorpX adds an executable C, which runs the application.
- CorpX will try to license proprietary the most they can (this enters the definition of
'CorpX', heh.)
The copyleft-next licensor can only: prove that libB is a "Derived Work", or fail to. In
the second case, they cannot rely on anything else (not CS, not section 5 either), to
require libB code to be free. I absolutely expect libB to be under copyleft-next (or
copyleft-next-compatible, or FOSS in some way - as licensor I'd make an 'exception' if
asked).
CorpX will argue that libB is a 'Separate Work', the *work which uses the copylefted library*.
If they succeed, there was nothing to bind 'Separate Works' under the license, because
the code of libB is: not under CS (i), not under CS (ii), and *NOT* under CS (iii). And,
it's not under section 5 (if it's not "Derived Work").
Does libB enter the scope of 'Derived Work'? No... it doesn't modify, adapt, translate.
It doesn't (per my hypothesis) add some more math functions, or improve them. It adds a
UI for it... It doesn't 'contain' (as far as I can tell, unless we claim that it "includes"
libA files in programmatic sense). I could (and would) claim it's "based on"... but
I feel it's easy to argue the term is so vague.
So CorpX gets away with it. IMO, anyway.

2) It's not entirely clear to me what does this language achieve:
"If you Distribute a Derived Work, you must license the entire Derived
Work as a whole under this License."
compared to:
"If you Distribute a Derived Work, you must license the Derived Work under
this License."
I'm trying to add the same requirement for Works which Use the Received Work,
but I'm not adding the 'entire' qualificative... Not sure. It seems to me
it's already covered by CS, considering also that DW and DU are under 'source
code' from CS(i) (and their build scripts under CS(ii)).

Signed-off-by: Engel Nyst <engel.nyst@gmail.com>