Add support for archives

Now that we have an policy option since 4192a2da (thanks to @dkg), it would be nice to add support for archives in MAT2.

• Implement archive support
  • zip
  • tar.gz
  • tar.bz2
  • tar.xz
  • tar (!39 (merged))
    • Handle path traversal issues ( 95169906 )
    • Handle symlink attacks ( 95169906 )
    • All the shits mentioned here
• Add tests
  • Add valid tests (those could be created at runtime by the testsuite)
  • Add corrupted archives
  • Add valid zip containing invalid files
  • Add archives containing read-only files
• Add documentation