Update to 2.6
    
    - New upstream release 2.6:
      - Fix insecure ElGamal key generation (launchpad bug #985164, CVE-2012-2417)
      - Huge documentation cleanup
      - Added more tests, including test vectors from NIST 800-38A
      - Remove broken MODE_PGP, which never actually worked properly
      - A new mode, MODE_OPENPGP, has been added for people wishing to write
        OpenPGP implementations (see also launchpad bug #996814)
      - Fix: getPrime with invalid input causes Python to abort with fatal error
        (launchpad bug #988431)
      - Fix: Segfaults within error-handling paths (launchpad bug #934294)
      - Fix: Block ciphers allow empty string as IV (launchpad bug #997464)
      - Fix DevURandomRNG to work with Python3's new I/O stack
      - Remove automagic dependencies on libgmp and libmpir; let the caller
        disable them using args
      - Many other minor bug fixes and improvements
    - Drop upstream patches