Support tar with pax header on windows by using python to etxract tars

Z7 still not supports tar files with pax headers. This is an issue as all recent Qt released tarballs where using it. For Windows we had to switch to the .zip files which we can't use on unix (permissions). The patch tries to continue to use 7z for the compression and python for the tar file.

The code uses hard links, as sym links are still not really supported on Windows. Before this change we had to resolve the sym links after the tar was extracted.