bug#15849: 24.3.50; lexical-binding in first line ugly

[Helmut Eller]

Emacs doesn't let be put the lexical-binding: t at the end of the file.
The manual says in (elisp)Lexical Binding:

  "Note that unlike other such variables, this one must be set in the
   first line of a file."

But in (elisp)Library Headers it says this:

     The very first line should have this format:
  
       ;;; FILENAME --- DESCRIPTION
  
  The description should be contained in one line.  If the file needs a
  `-*-' specification, put it after DESCRIPTION.  If this would make the
  first line too long, use a Local Variables section at the end of the
  file.

Clearly the manual contradicts itself.  My first line is already full
and putting the lexical-binding marker there is just plain ugly.  Please
provide another way to specify lexical binding. Something like a
declaration (IMO, the Right Thing):

  (declaim (lexical-binding t))

or some magic comment like

  ;;;###lexical-binding

that doesn't need to be in the first line.