openflow_input: add bsn_gentable extension and tests

See the documentation in openflow_input/bsn_gentable.
diff --git a/openflow_input/bsn_tlv b/openflow_input/bsn_tlv
new file mode 100644
index 0000000..3f39ed3
--- /dev/null
+++ b/openflow_input/bsn_tlv
@@ -0,0 +1,55 @@
+// Copyright 2013, Big Switch Networks, Inc.
+//
+// LoxiGen is licensed under the Eclipse Public License,
+// version 1.0 (EPL), with the following special exception:
+//
+// LOXI Exception
+//
+// As a special exception to the terms of the EPL, you may
+// distribute libraries generated by LoxiGen (LoxiGen Libraries)
+// under the terms of your choice, provided that copyright and
+// licensing notices generated by LoxiGen are not altered or removed
+// from the LoxiGen Libraries and the notice provided below is (i)
+// included in the LoxiGen Libraries, if distributed in source code
+// form and (ii) included in any documentation for the LoxiGen
+// Libraries, if distributed in binary form.
+//
+// Notice: "Copyright 2013, Big Switch Networks, Inc.
+// This library was generated by the LoxiGen Compiler."
+//
+// You may not use this file except in compliance with the EPL or
+// LOXI Exception. You may obtain a copy of the EPL at:
+//
+// http://www.eclipse.org/legal/epl-v10.html
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an "AS
+// IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+// express or implied. See the EPL for the specific language
+// governing permissions and limitations under the EPL.
+
+#version 4
+
+struct of_bsn_tlv_port : of_bsn_tlv {
+    uint16_t type == 0;
+    uint16_t length;
+    of_port_no_t value;
+};
+
+struct of_bsn_tlv_mac : of_bsn_tlv {
+    uint16_t type == 1;
+    uint16_t length;
+    of_mac_addr_t value;
+};
+
+struct of_bsn_tlv_rx_packets : of_bsn_tlv {
+    uint16_t type == 2;
+    uint16_t length;
+    uint64_t value;
+};
+
+struct of_bsn_tlv_tx_packets : of_bsn_tlv {
+    uint16_t type == 3;
+    uint16_t length;
+    uint64_t value;
+};