Howto implement chacha20-poly1305?

[Stef Bon]

Well I've got it working. It has been an allignment issue.

It looks to me that the code Jussi has written is correct.

I had to find out that the manner to determine padding has also
changed. The chacha20poly1305 has to two ciphers,
the data of the main cipher (starting at byte 4) has to be alligned,
which is --not-- documented at all.

If you want me to test the performance compared to other ciphers, let me know.

Stef