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/tests/mgcp/mgcpgw_client_test.ok b/tests/mgcp/mgcpgw_client_test.ok
new file mode 100644
index 0000000..d35f2d6
--- /dev/null
+++ b/tests/mgcp/mgcpgw_client_test.ok
@@ -0,0 +1,31 @@
+
+===== test_crcx =====
+composed:
+-----
+CRCX 1 17@mgw MGCP 1.0

+C: 2a

+L: p:20, a:AMR, nt:IN

+M: loopback

+
+-----
+composed response:
+-----
+200 1 OK

+I: 1
+
+v=0

+o=- 1 23 IN IP4 10.9.1.120

+s=-

+c=IN IP4 10.9.1.120

+t=0 0

+m=audio 16002 RTP/AVP 98

+a=rtpmap:98 AMR/8000

+a=ptime:20

+
+-----
+response cb received:
+  head.response_code = 200
+  head.trans_id = 1
+  head.comment = OK
+  audio_port = 16002
+Done