Implement IuCS (large refactoring and addition)

osmo-nitb becomes osmo-msc
add DIUCS debug log constant
add iucs.[hc]
add msc vty, remove nitb vty
add libiudummy, to avoid linking Iu deps in tests
Use new msc_tx_dtap() instead of gsm0808_submit_dtap()
libmgcp: add mgcpgw client API
bridge calls via mgcpgw

Enable MSC specific CTRL commands, bsc_base_ctrl_cmds_install() still needs to
be split up.

Change-Id: I5b5b6a9678b458affa86800afb1ec726e66eed88
diff --git a/include/openbsc/common.h b/include/openbsc/common.h
new file mode 100644
index 0000000..d91b3d3
--- /dev/null
+++ b/include/openbsc/common.h
@@ -0,0 +1,6 @@
+#pragma once
+
+enum nsap_addr_enc {
+	NSAP_ADDR_ENC_X213,
+	NSAP_ADDR_ENC_V4RAW,
+};