Using "-*- encoding:utf-8 -*-" doesn't really set the file encoding
for Emacs. It will even prompt the user when opening a compiled file:

  The local variables list in foo.mak.py
  contains values that may not be safe (*).

  Do you want to apply it?  You can type
  y  -- to apply the local variables list.
  n  -- to ignore the local variables list.

  !  -- to apply the local variables list, and permanently mark these
        values (*) as safe (in the future, they will be set automatically.)

    * encoding: utf-8

The problem is that Emacs looks for a file variable named "coding" and
it doesn't know about "encoding":

  http://www.gnu.org/software/emacs/manual/html_node/emacs/Specify-Coding.html

This is no doubt why Python recognizes "coding:" by itself:

  http://www.python.org/dev/peps/pep-0263/

This change makes the code generator output "# -*- coding:%s -*-" and
updates the documentation and examples to match this style.