NULL module handle for LoadXXX() supported.

  If you pass NULL as the module handle to the LoadXXXX() functions, then
MEWEL will try to open the application's EXE file, read the resource from
the EXE file, and close it. This means that you no longer need to call
OpenResourceFile(NULL) to open an EXE file.

  This change improved portability between MEWEL and MS Windows. For
instance, look at the following code :

#ifdef MEWEL
  hInstance = 0;
#endif
  LoadString(hInstance, IDSNAME, (LPSTR) szAppName, 10);

This will word under both MEWEL and Windows.