Implicit decode cause UnicodeDecodeError

Python already works with encoded strings. Thus when calling encode an implicit
decode is called and cause UnicodeDecodeError if non-ASCII chars are used. See
http://docs.python.org/2/howto/unicode.html#the-unicode-type
expose a decode problem with utf8 chars in code
Merge branch 'Fix_decode' into utf8-in-code

* Fix_decode:
  Implicit decode cause UnicodeDecodeError

Conflicts:
	code/wiki2beamer