* lisp/progmodes/python.el (python-shell-get-buffer): New function.

* lisp/progmodes/python.el (python-shell-get-buffer): New function.
(python-shell-get-process): Use it.
(python-shell-send-string): Always use utf-8 and add a cookie to tell
Python which encoding was used.  Don't split-string since we only care
about the first line.  Return the temp-file, if applicable.
(python-shell-send-region): Tell compile.el how to turn locations in
the temp-file into locations in the source buffer.