Add Conn.Close

conn.go

@@ -101,3 +101,9 @@ func (c *Conn) WriteAttrs(attrs []Attr) error {
 	c.bufs.Put(buf)
 	return err
 }
+
+// Close the underlying connection. After this, all attempts to write onto the
+// connection will return an error.
+func (c *Conn) Close() error {
+	return c.s.Close()
+}