Add sshchat dependencies in vendor

vendor/github.com/shazow/rateio/doc.go

@@ -0,0 +1,29 @@
+/*
+Package rateio provides an io interfaces for rate-limiting.
+
+This can be used to apply rate limiting to any type that implements an io-style interface.
+
+For example, we can use it to restrict the reading rate of a net.Conn:
+
+	type limitedConn struct {
+		net.Conn
+		io.Reader // Our rate-limited io.Reader for net.Conn
+	}
+
+	func (r *limitedConn) Read(p []byte) (n int, err error) {
+		return r.Reader.Read(p)
+	}
+
+	// ReadLimitConn returns a net.Conn whose io.Reader interface is rate-limited by limiter.
+	func ReadLimitConn(conn net.Conn, limiter rateio.Limiter) net.Conn {
+		return &limitedConn{
+			Conn:   conn,
+			Reader: rateio.NewReader(conn, limiter),
+		}
+	}
+
+Then we can use ReadLimitConn to wrap our existing net.Conn and continue using
+the wrapped version in its place.
+
+*/
+package rateio