* import.c (get_module): total rewrite, to ensure proper search order: for

each dir in sys.path, try each possible extension.  (Note: C extensions
  are loaded before Python modules in the same directory, to allow having
  a C version used when dynamic loading is supported and a Python version
  as a back-up.)
* import.c (reload_module): test for error from getmodulename()
* moduleobject.c: implement module name as dict entry '__name__' instead
  of special-casing it in module_getattr(); this way a module (or
  function!) can access its own module name, and programs that know what
  they are doing can rename modules.
* stdwinmodule.c (initstdwin): strip ".py" suffix of argv[0].