Release 3.1.0

Release 2.27.1

- [API] New knob to set outgoing packet batch size.
- Aborted connection now become tickable immediately.
- Abort connection when HTTP/3 frame cannot be opened (can only happen
when malloc fails).

Release 2.16.1

- [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.

Rename test/unittests to tests/ and test/ to bin/