Win32: shortpathname to longpathname

[Jim Tittsler]

I wrap my cross platform application up with py2exe on Windows, and
have the installer associate a particular file type with it.  When a
user double clicks on a document to launch my application, Windows
appears to pass me the "short" Windows pathname.  How can I convert to
the long version of the pathname?  (Ideally using the standard library
rather than win32all AKA pywin32.)