Feature: Variable GUI scale.

GUI scale is now variable from 100% to 500%, and no longer restricted to
powers-of-2.

src/openttd.cpp

@@ -756,7 +756,9 @@ int openttd_main(int argc, char *argv[])
 
 	/* Initialize the zoom level of the screen to normal */
 	_screen.zoom = ZOOM_LVL_NORMAL;
-	UpdateGUIZoom();
+
+	/* The video driver is now selected, now initialise GUI zoom */
+	AdjustGUIZoom(false);
 
 	NetworkStartUp(); // initialize network-core