Add global option for showing window title on titlebar

When the window title from current session is emtpy, fallback to using
tab title.

CCBUG: 162326
REVIEW: 103978

src/SessionController.cpp

@@ -1118,6 +1118,7 @@ void SessionController::sessionTitleChanged()
         title = _session->title(Session::NameRole);
 
     setTitle(title);
+    emit rawTitleChanged();
 }
 
 void SessionController::showDisplayContextMenu(const QPoint& position)
@@ -1579,5 +1580,16 @@ QRegExp SearchHistoryTask::regExp() const
     return _regExp;
 }
 
+QString SessionController::userTitle () const
+{
+    if ( _session) {
+        return _session->userTitle();
+    }
+    else
+    {
+        return QString();
+    }
+}
+
 #include "SessionController.moc"