TODO list for draft-11

[martinthomson]

P1 - Will break if not fixed

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

P2 - Might break if not fixed

• [x] 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)
• [x] Exempt stream 0 from flow control (check this)
• [ ] Send ACK in Retry packet

P3 - OK without

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