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/debug.h b/include/openbsc/debug.h
index 3feb7c3..de00b29 100644
--- a/include/openbsc/debug.h
+++ b/include/openbsc/debug.h
@@ -39,6 +39,7 @@
 	DV42BIS,
 	DPCU,
 	DVLR,
+	DIUCS,
 	Debug_LastEntry,
 };