TODO list for draft-11

[martinthomson]

P1 - Will break if not fixed

• BLOCKED frame includes reason for blocking
• Remove payload from PING
• Parse PATH_CHALLENGE/PATH_RESPONSE
• ACK frame is now 0xd
• Connection ID rework (two values, varlen, handshake key changes, etc...)
• Add length to long packet header
• Change QHKDF-Expand
• Mint to draft-28

P2 - Might break if not fixed

• Max stream count transport parameters (currently max stream ID)
• Generate PATH_RESPONSE
• Send only 3 packets in server handshake (implies use of PATH_CHALLENGE or HRR - Ugh)
• Exempt stream 0 from flow control (check this)
• Send ACK in Retry packet

P3 - OK without

• Send ACK delay transport parameter
• Grease version negotiation
• Allow empty STREAM frames (this is in -12)
• Remove implicit open (might return after Kista)
• Send CONNECTION_CLOSE when handshake fails
• Server preferred address