Patch implementing an alternate approach: support automatically
importing __main__ when sys.argv[0] is an importable path.  This allows
zip files, directories, and any future importable locations (e.g. URLs)
to be used on the command line.  Note that this also means that you
don't need an option on the #! line in a zip file, which avoids hairy #!
issues on platforms like Linux (where a #! line can have at most one
argument).  __main__ is used instead of __zipmain__, since it is not
zipfile specific.