Cann now read and change SCID via env variable LSQUIC_CID. Format is a
string of up to 20 space separated numbers which are then parsed. Relies
on atoi, so be careful with invalid values for the numbers

- [API] Rename "0-RTT" to "session resumption." In IETF QUIC, "0-RTT"
  always refers to early data, meaning a request that the server can
  reply to in the very first return flight.  A more appropriate name
  for what we support on the client site is "session resumption," which
  is standard TLS terminology.  Later, when we add support for 0-RTT
  (early data), we can use the 0-RTT terminology again, this time in
  proper context.
- [BUGFIX] Do not set certificate callback if ea_lookup_cert is NULL.
- [BUGFIX] Make connection tickable when it's marked as closed.
- [BUGFIX] Fail certificate lookup if SNI is not present in HTTP mode.
- Several documentation fixes and improvements.
- Minor code cleanup.

- [BUGFIX] Infinite loop in stream: advance read offset when discarding data.
- [OPTIMIZATION] Header protection: only initialize cipher once.
- [OPTIMIZATION] Batch header protection application.

- [FEATURE] QUIC and HTTP/3 Internet Draft 29 support.
- [BUGFIX] Check that scheduled packets are also sendable when
  calculating a connection's "tickable" property.
- [BUGFIX] Don't count scheduled packets as in-flight when pacer is
  checked on tick.
- gQUIC: delay calling on_new for pushed stream until headers are
  available.
- Allow nested calls to lsquic_engine_connect().

- [OPTIMIZATION] Stash up to two reordered packets in IETF mini conn
  instead of dropping them.
- [BUGFIX] Crash: check decrypt context before using it.  This regression
  was introduced in 2.16.2.

- [BUGFIX] ID-28: do not use TLS middlebox compatibility mode in
  ClientHello.  This change requires using a newer version of BoringSSL.
- [BUGFIX] Free connections in Advisory Tick Time Queue in engine dtor.
- [BUGFIX] IETF QUIC client: narrow migration check to a single path.
- [BUGFIX] NULL dereference: set function pointers for alarm for path
  challenges 2 and 3.
- [BUGFIX] HTTP/3 headers may be followed immediately by trailers.
- [BUGFIX] Log messages when SCID changes.

- [FEATURE] Use "no-progress timeout" after which connection is closed.
- [BUGFIX] Select new SCID when current SCID is retired.
- [BUGFIX] Don't warn about dropped Initial packet sequence gaps during
  mini/full handoff.
- [BUGFIX] Send correct conn error when HTTP/3 frame is truncated.
- [BUGFIX] Mini conn: consider amplification when deciding to return
  TICK_SEND.
- [BUGFIX] Don't double-count tag length in amplification logic.
- [BUGFIX] Don't squeeze out lone path challenges.
- [BUGFIX] Log messages dealing with scheduled packet queue squeezing.
- [BUGFIX] don't wipe current path if no path challenge responses
  come back.
- [BUGFIX] When path is reset, don't lose path_id which is used for
  logging.
- Downgrade flow control violations to info log level from warnings.
- Fix connection cap extra check, avoid checks in nested calls.
- Fix some unit tests when extra checks are enabled.
- Use ls-hpack 2.2.1.
- Turn off unconditional extra checks for IETF clients.
- Extra checks: don't verify sent size of hello packets.  Client
  changes DCID length and this check will fail.

Update ls-hpack to v2.2.0 and ls-qpack to v2.2.0 for lsxpack_header v206

(Not a typo: both libraries now happen to have the same version number.)

- [FEATURE] QUIC and HTTP/3 Internet Draft 28 support.
- [BUGFIX] Ignore Retry packets after other packets are decrypted
  successfully.
- [BUGFIX] Transport parameter decoding: CID no longer has 4-byte
  length minimum.
- http_client: fix and optimize lsxpack_header allocator.
- Drop support for Internet Draft 25.

* fix for BORINGSSL_LIB and BORINGSSL_INCLUDE paths with cmake

* fix boringssl lib search with different build dir

Android support

- [BUGFIX] ALPN-to-version mapping: do not skip h3-Q050.
- [BUGFIX] Frame reader: skip headers if target stream is closed.

- [BUGFIX] Fix amplification mitigation in 0-RTT case.
- [BUGFIX] IETF mini connection should not tickable if cannot send
  a packet due to amplification.
- [BUGFIX] Fail if active_connection_id_limit TP is smaller than 2.
- [BUGFIX] Qlog server certificates for IETF QUIC connections.
- [BUGFIX] Uninitialized struct padding usage in tokgen (benign).
- [BUGFIX] Incorrect argument to shi_lookup() (benign).

- [BUGFIX] In coalesced datagram, ignore packets whose CID does not match.
- [BUGFIX] Frame reader: skip headers if target stream is not found.
- [BUGFIX] Log message in QPACK decoder handler.

- [BUGFIX] Heed es_rw_once for pushed HTTP/3 streams.
- [BUGFIX] IETF client: set correct flags on bidirectional streams.
- [BUGFIX] Generate Cancel Stream QPACK instructions for abandoned
  streams.
- [BUGFIX] Do not call header callbacks after stream is closed.
- Use ls-qpack 2.1.1

- [BUGFIX] gQUIC: pass correct stream to hsi_create_header_set() callback.
- [BUGFIX] Use ls-hpack 2.1.1
- Improve stream code readability.
- Use ls-qpack 2.0.5

- [BUGFIX] Use ls-qpack 2.0.4
- [BUGFIX] Honor max packet size on the client and when path changes.
- http_server: fix prepare_decode() function.

- [BUGFIX] Place connections on tickable queue when sending is reenabled.
- [BUGFIX] A connection is tickable if it has unsent packets.
- [BUGFIX] Heed peer's max_packet_size transport parameter.

- [API] Use lsxpack_header structure to send HTTP headers.
- [OPTIMIZATION] nocopy's readable_bytes() function.
- http_server: fix typo in error message
- Use ls-hpack 2.1.0.
- Use ls-qpack 2.0.0.

- [BUGFIX] ACK ping-pong: TIMESTAMP frame is not to be acked.

- [BUGFIX] Use of new lsxpack_header API's hsi_prepare_decode().

Fixed minor errors in windows build instructions

Thanks, Travis!

- [API] Use lsxpack_header structure to process incoming headers.
- [BUGFIX] Fix assertion when zero-padding Initial packet.
- [BUGFIX] Use idle timeout before we learn of peer's value.
- Use ls-hpack 2.0.0 -- has lsxpack_header changes.
- Use ls-qpack 0.14.0 -- new, common with ls-hpack, XXH seed (not used yet).
- Code cleanup: prefix exported functions with "lsquic_".

Link to external docs & update year