Patch #1318 by Amaury Forgeot d'Arc.

Updates to ctypes for python 3.0 to make the tests pass.
Notable changes are:
- return bytes instead of str8
- integers in range(256) are accepted as "one char string":
  libc.strchr("abcdef", 98) is now valid.
- directly use the wide-char version of the win32 function LoadLibrary.