Padding in Initial in -13

[larseggert]

This got unfixed in version -13.

The end of Section 4.4.1 says:

   The payload of an Initial packet includes a CRYPTO frame (or frames)
   containing a cryptographic handshake message, ACK frames, or both.

whereas Section 4.4.1.4 says:

   The payload of a UDP datagram carrying the Initial packet MUST be
   expanded to at least 1200 octets (see Section 8), by adding PADDING
   frames to the Initial packet and/or by combining the Initial packet
   with a 0-RTT packet (see Section 4.6).

So PADDING frames need to be allowed in Section 4.4.1 as part of the Initial packet.