First lsquic (not lsquic-client) release

Support Q039, Q043, Q046, and ID-22 version of HTTP/3

HPACK compression performance improvement

Release 1.21.2

- [OPTIMIZATION] HPACK: use history to improve compression performance

Bug fix, HPACK optimization

Release 1.21.1

- [BUGFIX] If FIN or RST not received, don't delay stream destruction.
- [OPTIMIZATION] Speed up HPACK encoder by using same hash value to
  search static and dynamic tables.

[FEATURE] Add support for Q046

Release 1.20.0

[FEATURE] Add support for Q046.

Elide stale ACK frames from packets in buffered queue

ACK frames placed in packets in buffered queues (optimization introduced in 1.17.15) can be preceded by an ACK frame generated later. In this case, the older ACK frame should not be sent out, as Chromium-based servers flags decrease in the ACK frame's Largest Observed value as an error.

Fix Akamai handshake

• [BUGFIX] Use correct public key from PUBS based on KEXS index.
• [BUGFIX] Check flags before dispatching writes, avoiding assert.
• [BUGFIX] Set :scheme to "https" (instead of "HTTP").

A couple of zero-RTT bug fixes

Release 1.19.4

- [BUGFIX] Check buffer bounds when looking up version in 0-RTT blob.
- [BUGFIX] http_client: don't fetch 0-rtt info if handshake failed.
- Log number of pacer calls at DEBUG, rather than NOTICE, level.

Zero-RTT bugfix release

• [BUGFIX] Begin negotiation with version provided in 0-RTT info.
• [BUGFIX] Version checking in zero_rtt deserialize function.

0-RTT support; bug fixes; Windows works again

• [FEATURE, API Change] 0-RTT support. Add function to export 0-RTT information; it can be supplied to a subsequent connect() call.
• [FEATURE] Add -0 flag to http_client to exercise 0-RTT support.
• [BUGFIX] Resuscitate the Windows build.
• [BUGFIX] Send HTTP settings (max header list size) if necessary.
• [BUGFIX] Buffered packets can contain ACK frames.
• [BUGFIX] Make packet writeable once all STREAM frames are elided.
• [BUGFIX] Fix potential null dereference when realloc fails.
• cmake: simplify build configuration.

Bug fixes and performance improvements

• [API Change] Can specify clock granularity in engine settings.
• [BUGFIX] Pacer uses fixed clock granularity. Since the change on 2018-04-09, it is not necessary to try to approximate the next tick time in the pacer: it can use fix clock granularity specified by the user.
• [BUGFIX] Do not tick constantly before handshake is done.
• [BUGFIX] Do not exit tick prematurely: reuse packet with ACK. Even if we cannot allocate more packets, we could still be able to write o one already allocated.
• [BUGFIX] Do not schedule pacer if there are no lost packets.