Fix a couple of issues with filename encodings.

Fix a couple of issues with filename encodings.

* Take into account the filesystem encoding for the zip export on *nix
  such that the representation of filenames in the zip archive is not
  mangled, when possible. This only concerns the way filenames are displayed
  as their creation in the filesystem was nevertheless correct.

* On Windows, try to obtain the command line parameters from the wide char
  representation by directly accessing the platform APIs through ctypes.
  This allows to also deal with filenames not exactly representable using
  the current code page and corrects a bug resulting in silently dropping
  those kind of filenames.