As in Champa. Use one main polling loop, not multiple, but execute each
poll asynchronously.

Enforces maxPayloadLength (by stashing packets that exceed the limit)
and should have lower latency because it does not wait for the maximum
delay every time.

Adds support for a one-packet "stash," and closes send queues when
expiring.

Increase send and receive window sizes.
https://repo.or.cz/champa.git/commit/d207527dd774f217cbb4ebdc2a1f4d3d3fc5e9d2

Higher defaults for smux MaxReceiveBuffer and MaxStreamBuffer.
https://repo.or.cz/champa.git/commit/5231ffeab1f701bdbebc9585a69b1c2db58b3e35

Increase queueSize to 256.
https://repo.or.cz/champa.git/commit/7d110808f0279c5130a7c5640cc472a00a679eff

Updated a test relating to the server_name extension when an IP address
is dialed.
https://github.com/refraction-networking/utls/pull/100

sync.Once does not prevent other goroutines from accessing a variable
that has not been defined yet.

We need to guard against concurrent modification of rt.rt, but once it
is set, we many concurrently call rt.rt.RoundTrip. The way this was
written before, it was preventing more than one RoundTrip from happening
at once. (Which was not noticeable, because the protocol serialized all
RoundTrips.)

To match documentation added in
7aa47e7f.

The crypto/tls server, since go1.12, requires that if a server_name
extension is present, it is not empty. With go1.12 and later, this test
was failing with
	proxy_test.go:95: local error: tls: unexpected message

The specific commit that added the empty server_name check was:
https://go-review.googlesource.com/c/go/+/144115
https://github.com/golang/go/commit/4c8b09e9183390d6ab80d3f53a9fe5f6ace92f06#diff-f2f5faeac5da94dc7735456f798177b53421f827b8bfc242b56f116b8e5c7e62R264
Note the comment "enforcing a couple more 'must not be empty' on the
unmarshaling side".

Wireshark also complains in a packet capture:
	[Expert Info (Warning/Protocol): Vector length 0 is smaller than minimum 1]

https://bugs.torproject.org/tpo/anti-censorship/pluggable-transports/meek/40002

This ought to have been removed in
bc887de6.

https://bugs.torproject.org/tpo/anti-censorship/pluggable-transports/meek/40002

When we receive a response that contains at least one packet, permit 2
immediate polls. Polls are also timeout-driven, using an expoentially
increasing delay as before.

github.com/refraction-networking/utls

Adds
	HelloFirefox_65
	HelloChrome_72
	HelloIOS_12_1

Clone is new in go1.13.
https://github.com/golang/go/issues/26013

This adds --quic-tls-cert and --quic-tls-key options to the server
(separate from --cert and --key); and a quic-tls-pubkey SOCKS arg (with
equivalent --quic-tls-pubkey command-line option) to the client.

This package defines how we encapsulate discrete discrete datagrams into
an HTTP request or response body, with optional padding.