implement basic ACK block parsing for QUIC 34 ACK frames

ref #182

frames/ack_range.go

@@ -0,0 +1,9 @@
+package frames
+
+import "github.com/lucas-clemente/quic-go/protocol"
+
+// AckRange is an ACK range
+type AckRange struct {
+	FirstPacketNumber protocol.PacketNumber
+	LastPacketNumber  protocol.PacketNumber
+}