WIP: MSC_Tests: Add SGs testcases

This extens MSC_Tests.ttcn with an initial set of SGs interface test
cases for RESET, LU, DETACH, PAGING, SMS and CSFB procedures

In particular the following testcases are added:

- TC_sgsap_reset: isolated reset procedure test
- TC_sgsap_lu: isolated location update with TMSI realloc
- TC_sgsap_lu_imsi_reject: location update, reject case
- TC_sgsap_lu_and_nothing: location update with failed TMSI realloc
- TC_sgsap_expl_imsi_det_eps: detach from EPS serveces
- TC_sgsap_expl_imsi_det_noneps: detach from non-EPS services
- TC_sgsap_paging_rej: isolated paging, reject case
- TC_sgsap_paging_subscr_rej: isolated paging, subscr rejects call
- TC_sgsap_paging_ue_unr: isolated paging, ue is unreachable
- TC_sgsap_paging_and_nothing: page, but don't respond
- TC_sgsap_paging_and_lu: check paging followed by an LU
- TC_sgsap_mt_sms: mobile terminated SMS through SGs Interface
- TC_sgsap_mo_sms: mobile originated SMS through SGs Interface
- TC_sgsap_mt_sms_and_nothing: trigger SMS, but don't respond to paging
- TC_sgsap_mt_sms_and_reject: trigger SMS, but reject paging
- TC_sgsap_unexp_ud: Send unexpected unitdata (SGs Association: NULL)
- TC_sgsap_unsol_ud: Send unsolicited unitdata (subscriber not in VLR)
- TC_bssap_lu_sgsap_lu_and_mt_call: LU on 2G, LU on SGs and CSFB call
- TC_sgsap_lu_and_mt_call: LU on SGs, and CSFB call

Change-Id: I38543c35a9e74cea276e58d1d7ef01ef07ffe858
Depends: osmo-msc I73359925fc1ca72b33a1466e6ac41307f2f0b11d
Related: OS#3645
diff --git a/library/SGsAP_Templates.ttcn b/library/SGsAP_Templates.ttcn
index 9526080..457481e 100644
--- a/library/SGsAP_Templates.ttcn
+++ b/library/SGsAP_Templates.ttcn
@@ -69,7 +69,10 @@
 		return omit;
 	} else if (istemplatekind(digits, "*")) {
 		return *;
+	} else if (istemplatekind(digits, "?")) {
+		return ?;
 	}
+	log("tr_SGsAP_IMSI: ", digits);
 	var template IMSI imsi := {
 		iEI := '00000001'B,
 		lengthIndicator := lengthof(digits)/2 + 1,