sipcall: Modify calls handling process

Integration of new security features implies modifications in call handling.
By default, when handling a call,  a SipCall object is created, but if ZRTP hooks
are activated, the call is dynamically subclassed, and becomes a SecureSipCall.

Refs #40939
diff --git a/src/org/sflphone/fragments/ConferenceDFragment.java b/src/org/sflphone/fragments/ConferenceDFragment.java
index c7ebb17..a889ccd 100644
--- a/src/org/sflphone/fragments/ConferenceDFragment.java
+++ b/src/org/sflphone/fragments/ConferenceDFragment.java
@@ -75,7 +75,7 @@
 
         
 
-        final AlertDialog a = new AlertDialog.Builder(getActivity()).setView(rootView).setTitle("Transfer " + call_selected.getParticipants().get(0).getContact())
+        final AlertDialog a = new AlertDialog.Builder(getActivity()).setView(rootView).setTitle("Transfer " + call_selected.getParticipants().get(0).getmContact())
                 .setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() {
                     public void onClick(DialogInterface dialog, int whichButton) {
 
@@ -136,7 +136,7 @@
             }
 
             if(calls.get(position).getParticipants().size() == 1){
-                tv.setText(calls.get(position).getParticipants().get(0).getContact().getmDisplayName());
+                tv.setText(calls.get(position).getParticipants().get(0).getmContact().getmDisplayName());
             } else {
                 tv.setText("Conference with "+ calls.get(position).getParticipants().size() + " participants");
             }