- Create a test for non-public SSH2 format.  We may have to roll our own.

- Implement SSH2 serialize.

- Test encrypted key files?

- DER format (PEM without the wrappers)

- Should we care about CryptX PEM interop?  libtomcrypt writes the data
  differently than OpenSSL, Crypto++, etc.  We could make a new Key type.

- File ticket with Net::SSH::Perl to use this.  This and a couple other
  changes can completely remove Math::Pari from its requirements.  I have
  done some simple testing that shows this works.

- Can we use the new key generation method if seed isn't given?

- Make the BufferWithInt helper package completely internal
