Release 3.1.0

[MISC] replace TAB with 4 spaces.

[WIP] use vcpkg for getopt; build windows shared lib enhancements (#350)

* fix MSVC compiler shared library issues - mostly around 'extern const'

* add vcpkg install getopt to appveyor-windows.yml

show appveyor where to get getopt from vcpkg (non-static lib to avoid LGPL violation)

* add missing else case in lsquic_shared_support.h for windows static lib path

* have cmake spit out it's version

have cmake copy dependent dlls to build dir for tests on windows (getopt.dll)

* copy getopt.dll dep for tests

added commented version that requires >= 3.21 but handles any dll deps

* try caching boringssl dir to reduce CI build time since it's always same commit specified in config file

define VCPKG_ROOT in env since I can't seem to find it by VCPKG_ROOT or VCPKG_INSTALLED_DIR in appveyor's cmake v3.16 + vcpkg

* make windows cache dependent on yml and cmd

* sync up with changes to ls-qpack

Release 2.29.3

- [BUGFIX] Do not send RESET_STREAM if writing to stream is already
finished.
- perf_client: wait for all ACKs before exiting.
- Improve how generated RESET_STREAM is logged.
- Fix compilation in different combos of adv_tick/conn_stats flags.
- Move qpack warning disablement into src/liblsquic/CMakeLists.txt.

Release 2.27.3

- [BUGFIX] gQUIC: do not destroy critical streams when connection is
closed. See issue #201.
- [BUGFIX] Drop #if LSQUIC_CONN_STATS from lsquic.h. See issue #211.
- [BUGFIX] Challenge cancellation when path validation fails.
- [BUGFIX] Do not send FIN if RST is scheduled to be sent on a stream.
- [BUGFIX] gQUIC's is_tickable() when connection is closing.
- [BUGFIX] Q050 processing of GOAWAY frames.

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 2.26.2

- [BUGFIX] Do not drop incoming data when STOP_SENDING is received.
- [BUGFIX] Receipt of STOP_SENDING should not cause read-reset.
- [BUGFIX] Allow stream writes after receiving RESET.
- [BUGFIX] Typo in stream: ANDing enum with wrong flag.
- [BUGFIX] Reset elision: do not use zero as special stream ID value,
for zero is a valid stream ID in IETF QUIC.
- [API] Add optional on_conncloseframe_received() callback.
- Use zero error code in RESET stream sent in response to STOP_SENDING.

Release 2.26.1

- [BUGFIX] Migration corner cases: drop or pad over path challenge
and response frames when necessary.
- Fix stream unit test.

Release 2.25.0

- [API, FEATURE] Add es_delay_onclose option to delay on_close until all
data is ACKed. Use new function lsquic_stream_has_unacked_data() to
learn whether peer acknowledged all data written to stream.
- [API] Add optional on_reset() stream callback to get notifications
when RESET or STOP_SENDING frames are received.
- [BUGFIX] On STOP_SENDING, make conn tickable is _writeable_, not
readable.

Release 2.23.3

- [BUGFIX] Update packetization threshold when writing to stream
after packet size is reduced following an RTO.

Fix unit tests

Release 2.20.0

- [FEATURE] QUIC and HTTP/3 Internet Draft 30 support.
- [FEATURE] Unreliable Datagram Extension support.
- [FEATURE] Adaptive congestion controller.
- [BUGFIX] Do not send MAX_STREAM_DATA frames on crypto streams.
- [BUGFIX] Fail with CRYPTO_BUFFER_EXCEEDED when too much CRYPTO
data comes in.
- [BUFFIX] Spin bit is now strictly per path; value is reset on
DCID change.
- [BUGFIX] Check that max value of max_streams_uni and
max_streams_bidi TPs is 2^60.
- [BUGFIX] Close IETF mini conn immediately if crypto session
cannot be initialized.
- Deprecate ID-28 (no browser uses it): it's no longer in the
default versions list.
- New programs duck_server and duck_client that implement the
experimental siduck-00 protocol. They quack!
- IETF crypto streams: don't limit ourselves from sending.
- Command-line programs: turn off QL loss bits if -G is used, as
Wireshark cannot decrypt QUIC packets when this extension is used.
- Turn all h3 framing unit tests back on.
- Fix malo initialization when compiled in no-pool mode.

Release 2.19.9

- [FEATURE] Add lsquic_stream_pwritev(). This function allows one to
reduce the number of system calls required to read a file from disk
by using lsquic_stream_pwritev() together with preadv(2).
- [BUGFIX] When stream is reset, it is writeable -- let user collect
the error.
- [BUGFIX] Calculate correct conn flow control if reading ends early.
- [BUGFIX] Remove stream from read and write queues on internal
shutdown. This is a regression introduced in 2.19.7.
- [BUGFIX] Swapped arguments in IETF RESET_FRAME generation.
- Turn off mini conn history when compiling with Visual Studio; this
allows the project to compile on Windows again.
- http_client: Add -3 flag to stop reading from streams early; code
cleanup.
- Don't use -Werror.

Release 2.19.5

- [BUGFIX] Generate frame record when moving an ACK from one buffered
packet to another.

Release 2.19.0

- [FEATURE] DPLPMTUD support. IETF connections now search for the
maximum packet size, improving throughput.
- [DEBUG] Record event in stream history when on_close() is called
in dtor.

Release 2.15.0

- [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.

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