[MLton] MLton library project licensing

[Stephen Weeks]

> The problem with the current license file is that the disclaimer talks
> about NEC explicitly.
...
> Therefore, our lawyer recommended that we add generic license and
> disclaimer passages after the NEC ones.  The generic text would be the
> same as the NEC text but subtitutes NEC with to "the above copyright
> holders".

Fine with me, as it is merely adding a disclaimer.  In fact, I think
it is fine to tweak the first paragraph of the license to, in effect,
add a restriction by generalizing NEC to "above copyright holders" as
well.  In the interest of presenting the simplest possible license to
users, I have copied MLton-LICENSE to NEC-LICENSE, and generalized the
MLton-LICENSE as suggested above.  Have a look at

  http://mlton.org/License

I believe that MLton-LICENSE is consistent with (i.e. a restriction
of) NEC-LICENSE and should meet the needs of future contributors.