[layers] NOLAYERS option at compile time. Unfinished.

git-svn-id: svn://pulkomandy.tk/GrafX2/branches/layers@1140 416bcca6-2ee7-4201-b75f-2eb2f807beb1

pages.h

@@ -30,6 +30,8 @@
 /////////////////////////// BACKUP ///////////////////////////////////////
 //////////////////////////////////////////////////////////////////////////
 
+extern T_Image Visible_image[2];
+extern T_Image Visible_image_depth_buffer;
 
 ///
 /// INDIVIDUAL PAGES
@@ -92,6 +94,8 @@ void Update_depth_buffer(void);
 void Redraw_layered_image(void);
 void Redraw_current_layer(void);
 
+void Update_screen_targets(void);
+
 ///
 /// STATISTICS
 ///