Merge branch 'master' into jgrpp

# Conflicts:
#	src/airport_gui.cpp
#	src/blitter/32bpp_anim_sse4.cpp
#	src/console_cmds.cpp
#	src/linkgraph/linkgraph_gui.cpp
#	src/newgrf_object.h
#	src/road_gui.cpp
#	src/widgets/road_widget.h
#	src/window.cpp

src/zoom_func.h

@@ -36,6 +36,17 @@ static inline int UnScaleByZoom(int value, ZoomLevel zoom)
 	return (value + (1 << zoom) - 1) >> zoom;
 }
 
+/**
+ * Adjust by zoom level; zoom < 0 shifts right, zoom >= 0 shifts left
+ * @param value value to shift
+ * @param zoom zoom level to shift to
+ * @return shifted value
+ */
+static inline int AdjustByZoom(int value, int zoom)
+{
+	return zoom < 0 ? UnScaleByZoom(value, ZoomLevel(-zoom)) : ScaleByZoom(value, ZoomLevel(zoom));
+}
+
 /**
  * Scale by zoom level, usually shift left (when zoom > ZOOM_LVL_NORMAL)
  * @param value value to shift