[MLton] Emacs mode for editing ML Basis files

[Stephen Weeks]

> doc/emacs  --->  ide/emacs
> doc/mlton.spec  --->  package/rpm/mlton.spec
> debian  --->  package/debian  
> freebsd  --->  package/freebsd
> doc/cmcat  --->  util/cmcat   
> doc/cm2mlb  --->  util/cm2mlb

Looks good.  It may cause a little problem with packaging stuff,
since, e.g., the debian directory expects to be at the top level.  But
I think things like that are better fixed by Makefile targets than by
constraing ourselves by others' layouts.