Allow multiple overlays

This effectively allows us to support popup dialogs and the like.

Change-Id: Iafb3fa60ed635287cb59dce118f74dc8f2a4e60a
diff --git a/gui/gui.cpp b/gui/gui.cpp
index c755a98..ebd7053 100644
--- a/gui/gui.cpp
+++ b/gui/gui.cpp
@@ -734,6 +734,7 @@
 
 int gui_changeOverlay(std::string overlay)
 {
+	LOGINFO("Set overlay: '%s'\n", overlay.c_str());
 	PageManager::ChangeOverlay(overlay);
 	gForceRender.set_value(1);
 	return 0;