Changes for CryptX

TODO:
        - http://www.cpantesters.org/cpan/report/f9dc6958-accc-11e2-99fc-de953c106faf
        - maybe add xxx_b64url alternatives (e.g. sha1_b64url ...)
        - croak with the "real caller" (Crypt::Mac::*, Crypt::Mode::*, ...)
        - croak when mode does not call start_(en|de)crypt

0.008   2013/05/02
        - fixed prng test failures
        - Crypt::Digest::* croaks with the "real caller" (not a nice solution)

0.007   2013/04/23
        - Crypt::PRNG supports add_entropy() - without params
        - Crypt::PRNG fork-safe & thread-safe
        - random_string has default $len = 20
        - doc fixes
        - cpan tester failure fix for pk_dsa.t

0.006   2013/04/19
        - added Crypt::KeyDerivation
        - Win64 compatibility

0.005   2013/04/18
        - added Crypt::PRNG::Fortuna|RC4|Sober128|Yarrow
        - added Crypt::PK::RSA|DSA|ECC|DH

0.004   2013/04/16
        - removing illegal Crypt::Random

0.003   2013/04/16
        - added Crypt::Mode::CBC|CFB|CTR|ECB|OFB
        - added Crypt::AuthEnc::CCM|EAX|GCM|OCB

0.002   2013/04/11
        - first release on CPAN