Put back a render_settings.h include until we untangle more headers

include/plotter.h

@@ -38,17 +38,13 @@
 #include <page_info.h>
 #include <gal/color4d.h>
 #include <eda_item.h>       // FILL_T
+#include <render_settings.h>
 
 class COLOR_SETTINGS;
 class SHAPE_POLY_SET;
 class SHAPE_LINE_CHAIN;
 class GBR_NETLIST_METADATA;
 
-namespace KIGFX
-{
-    class RENDER_SETTINGS;
-}
-
 using KIGFX::RENDER_SETTINGS;
 
 /**