add buttons on videooverlay and fix multi account

this patch adds buttons to switch to welcome page and settings
page whilst in a call.
The client was lacking this fonctionnality, in comparison to the
gnome client.

This patch also fixes the comportment of the smartlist responding
to these new possible states (including changing account during
a call).

Change-Id: I9c620d83ae0daf75f3ffc64205299006686807f1
Reviewed-by: Anthony Léonard <anthony.leonard@savoirfairelinux.com>
diff --git a/videooverlay.h b/videooverlay.h
index 4b354ef..c525a3a 100644
--- a/videooverlay.h
+++ b/videooverlay.h
@@ -56,6 +56,8 @@
     void on_qualityButton_clicked();
     void on_addToContactButton_clicked();
     void on_recButton_clicked();
+    void on_videoBackBtn_clicked();
+    void on_videoCfgBtn_clicked();
 
 private:
     Ui::VideoOverlay* ui;
@@ -66,5 +68,7 @@
 
 signals:
     void setChatVisibility(bool visible);
+    void videoBackBtnClicked();
+    void videoCfgBtnClicked();
 };