Add RelayAddressGeneratorPortRange

New RelayAddressGenerator that only listens in a certain range

Update module stretchr/testify to v1.6.1

Generated by renovateBot

Transaction result blocking send

This fixes a race condition where a transaction result could attempt to
send on the result channel before it had a receiver (i.e. before
transaction.WaitForResult has been called), causing the caller to never
see the result. This was very likely to occur when when two peers and
the STUN/TURN server were on the same host.

Fix send on closed channel in Client

Protect concurrent run of
trMap.Find, trMap.CloseAndDeleteAll, and trMap.Delete.

Add dedicated TCP TURN Client

Also update .goreleaser binary names to be more
self documenting

Resolves pion#87

Release /v2

We may have issues still, but this contains all the
features we care about!

Add STUNConn. Wrapping net.Conn for TURN Clients

This allow us to use a net.Conn (like TCPConn) as the conn
for a TURN client.

Relates to pion#1

Fix incorrect warning

Resovles pion#97

Bump pion/stun

Go v1.13 compatibility

Removing outer locks around setLifetime

Removing the outer locks around the setLifetime call which
causes a deadlock as setLifetime wants the same lock.