Update to latest trunnel

src/ext/trunnel/trunnel-impl.h

src/ext/trunnel/trunnel.c

src/ext/trunnel/trunnel.h

src/trunnel/ed25519_cert.c

src/trunnel/ed25519_cert.h

src/trunnel/link_handshake.c

src/trunnel/link_handshake.h

src/trunnel/pwbox.c

src/trunnel/pwbox.h