Change the panel menu descriptions to better identify them

The "Main Menu" becomes "Compact Menu", since it is indeed the most compact menu available for MATE.

The "Menu Bar" becomes "Classic Menu" since this is what most users identify as the classic menu used in GNOME2/MATE. The description more clearly articulates the menu features.

mate-panel/panel-addto.c

@@ -150,8 +150,8 @@ static PanelAddtoItemInfo special_addto_items [] = {
 static PanelAddtoItemInfo internal_addto_items [] = {
 
 	{ PANEL_ADDTO_MENU,
-	  N_("Main Menu"),
-	  N_("The main MATE menu"),
+	  N_("Compact Menu"),
+	  N_("A compact menu"),
 	  PANEL_ICON_MAIN_MENU,
 	  PANEL_ACTION_NONE,
 	  NULL,
@@ -162,8 +162,8 @@ static PanelAddtoItemInfo internal_addto_items [] = {
 	  TRUE },
 
 	{ PANEL_ADDTO_MENUBAR,
-	  N_("Menu Bar"),
-	  N_("A custom menu bar"),
+	  N_("Classic Menu"),
+	  N_("The classic Applications, Places and System menu bar"),
 	  PANEL_ICON_MAIN_MENU,
 	  PANEL_ACTION_NONE,
 	  NULL,