This adds a compatible API for BoringSSL's QUIC support, based
on the current |draft-ietf-quic-tls|.

Based on BoringSSL commit 3c034b2cf386b3131f75520705491871a2e0cafe
Based on BoringSSL commit c8e0f90f83b9ec38ea833deb86b5a41360b62b6a
Based on BoringSSL commit 3cbb0299a28a8bd0136257251a78b91a96c5eec8
Based on BoringSSL commit cc9d935256539af2d3b7f831abf57c0d685ffd81
Based on BoringSSL commit e6eef1ca16a022e476bbaedffef044597cfc8f4b
Based on BoringSSL commit 6f733791148cf8a076bf0e95498235aadbe5926d
Based on BoringSSL commit 384d0eaf1930af1ebc47eda751f0c78dfcba1c03
Based on BoringSSL commit a0373182eb5cc7b81d49f434596b473c7801c942
Based on BoringSSL commit b1b76aee3cb43ce11889403c5334283d951ebd37

Create quic_change_cipher_state() that does the minimal required
to generate the QUIC secrets. (e.g. encryption contexts are not
initialized).

Try to reduce unneeded whitespace changes and wrap new code to 80 columns.
Reword documentation to attempt to improve clarity.
Add some more sanity checks and clarifying comments to the code.
Update referenced I-D versions.

QUIC does not use the TLS KeyUpdate message/mechanism, and indeed
it is an error to generate or receive such a message.  Add the
necessary checks (noting that the check for receipt should be
redundant since SSL_provide_quic_data() is the only way to provide
input to the TLS layer for a QUIC connection).

For now, just test that we don't generate any, since we don't really
expose the mechanics for encrypting one and the QUIC API is not
integrated into the TLSProxy setup.

Make all data supplied via SSL_provide_quic_data() pass through an
internal buffer, so that we can handle data supplied with arbitrary
framing and only parse complete TLS records onto the list of QUIC_DATA
managed by quic_input_data_head/quic_input_data_tail.

This lets us remove the concept of "incomplete" QUIC_DATA structures,
and the 'offset' field needed to support them.

However, we've already moved the provided data onto the buffer by
the time we can check for KeyUpdate messages, so defer that check
to quic_get_message() (where it is adjacent to the preexisting
ChangeCipherSpec check).

To avoid extra memory copies, we also make the QUIC_DATA structures
just store offsets into the consolidated buffer instead of having copies
of the TLS handshake messages themselves.

The QUIC-TLS spec requires that TLS handshake messages do not cross
encryption level boundaries, but we were not previously enforcing this.

Prefix the shared library version with 17 (for 'Q'), to allow this
version to be used alongside a standard OpenSSL distribution

Add +quic to the version (i.e. build metadata)

* QUIC: Add early data support

This commit adds SSL_set_quic_early_data_enabled to add early data
support to QUIC.

This commit makes SSL_provide_quic_data accept 0 length data, which
matches BoringSSL behavior.

Fixes quictls#9

…tls#16)

…s#18)

Can be squashed with `QUIC: Swap around README files`

Fixes quictls#2 and quictls#3 and quictls#22 

Updates `Configure` script to disable QUIC with `no-bulk` and `no-ec`
Updates build.info doc docs
Fixes an issue with extension defintions and `no-quic`

As DTLS has changed, so too must QUIC.

We now let you call this function outside of the handshake, to provide
post-handshake QUIC data.

We also no longer have the limitation that the application must provide
the TLS handshake message header in a single call.

The limit on the amount of queued data is to avoid being an amplification
vector, specifically.

The QUIC APIs have no need to interact with TLS ciphers, since
QUIC records use different cryptographic protections than TLS ciphers.

Fixes quictls#55
Had to fixup tests because SSL_accept() eventually calls SSL_clear() and
it was removing the inital ClientHello sent via SSL_provide_quic_data()
from the server SSL.

Undo SSL_clear() changes in test
Break apart SSL_clear() into SSL_clear_quic() and SSL_clear_not_quic()
In SSL_clear(), call both functions
In SSL_accept(), call SSL_clear_not_quic()
Don't make the new functions public.

Add link to OMCs plans.
OpenSSL 3.0 is released, update tense.
Fix some typos.
Make relative URLs absolute.