Python3.2: Iterator error message was not changed before Python3.3
Debian: Support both xz and gz for source archives.
Standalone: Avoid using importlib for Python2.6 portability.
Standalone: Fixup for Python3.2 which outputs frozen modules too.
Windows: Added support for determining memory usage as well.
Minor cleanup

* Comparing against "os.name" to detect Windows, because that is done like
  that in all the other code.

* Made the else branch for other platforms explicit.