o added new features:
o -G: generate a new paramsfile that produces the same
key as the old paramsfile,
o ffs verify_method,
o multiple keygen methods that are xor'ed together
(for n-factor authentication), and
o calibrating the iteration count of PKCS#5 PBKDF2 to
the current machine's speed.
o changed paramsfile format to allow for the new features.
o replaced open-coded parser with yacc grammar.
o lots of supporting changes.
o updated documentation to reflect new features and new
paramsfile format.
