IPA_Emulation: Change default params to const, export them and use empty string

This means we rather return an empty string in CCM_IDTAG responses,
rather than crashing due to non-defined record members.
diff --git a/library/IPA_Emulation.ttcn b/library/IPA_Emulation.ttcn
index 92e0a35..696019e 100644
--- a/library/IPA_Emulation.ttcn
+++ b/library/IPA_Emulation.ttcn
@@ -57,7 +57,7 @@
 	var boolean g_is_bsc_mgw;
 
 	var IpaMode g_mode;
-	var IPA_CCM_Parameters	g_ccm_pars := c_default_ccm_pars;
+	var IPA_CCM_Parameters	g_ccm_pars := c_IPA_default_ccm_pars;
 }
 
 type record IPA_CCM_Parameters {
@@ -73,22 +73,22 @@
 	charstring	osmo_rand optional
 }
 
-private const IPA_CCM_Parameters c_default_ccm_pars := {
-	ser_nr := omit,
+const IPA_CCM_Parameters c_IPA_default_ccm_pars := {
+	ser_nr := "",
 	name := "mahlzeit",
-	location1 := omit,
-	location2 := omit,
-	equip_version := omit,
-	sw_version := omit,
-	ip_addr := omit,
-	mac_addr := omit,
+	location1 := "",
+	location2 := "",
+	equip_version := "",
+	sw_version := "",
+	ip_addr := "",
+	mac_addr := "",
 	unit_id := "0/1/2",
-	osmo_rand := omit
+	osmo_rand := ""
 };
 
 function f_connect(charstring remote_host, PortNumber remote_port,
 		   charstring local_host, PortNumber local_port,
-		   IPA_CCM_Parameters ccm_pars := c_default_ccm_pars) runs on IPA_Emulation_CT {
+		   IPA_CCM_Parameters ccm_pars := c_IPA_default_ccm_pars) runs on IPA_Emulation_CT {
 	var Result res;
 	res := IPA_CodecPort_CtrlFunct.f_IPL4_connect(IPA_PORT, remote_host, remote_port,
 						local_host, local_port, 0, { tcp:={} });
@@ -102,7 +102,7 @@
 }
 
 function f_bind(charstring local_host, PortNumber local_port,
-		IPA_CCM_Parameters ccm_pars := c_default_ccm_pars) runs on IPA_Emulation_CT {
+		IPA_CCM_Parameters ccm_pars := c_IPA_default_ccm_pars) runs on IPA_Emulation_CT {
 	var Result res;
 	res := IPA_CodecPort_CtrlFunct.f_IPL4_listen(IPA_PORT, 
 						local_host, local_port, { tcp:={} });
@@ -240,9 +240,10 @@
 }
 
 function main_client(charstring remote_host, PortNumber remote_port,
-		     charstring local_host, PortNumber local_port) runs on IPA_Emulation_CT {
+		     charstring local_host, PortNumber local_port,
+		     IPA_CCM_Parameters ccm_pars := c_IPA_default_ccm_pars) runs on IPA_Emulation_CT {
 	g_mode := IPA_MODE_CLIENT;
-	f_connect(remote_host, remote_port, local_host, local_port);
+	f_connect(remote_host, remote_port, local_host, local_port, ccm_pars);
 	ScanEvents();
 }