Merge branch 'save_ext' into enhanced_viewport_overlay

# Conflicts:
#	src/smallmap_gui.cpp

src/smallmap_gui.h

@@ -106,6 +106,7 @@ protected:
 	uint8 refresh;   ///< Refresh counter, zeroed every FORCE_REFRESH_PERIOD ticks.
 	LinkGraphOverlay *overlay;
 
+	static void BreakIndustryChainLink();
 	Point SmallmapRemapCoords(int x, int y) const;
 
 	/**
@@ -196,7 +197,7 @@ public:
 	friend class NWidgetSmallmapDisplay;
 
 	SmallMapWindow(WindowDesc *desc, int window_number);
-	virtual ~SmallMapWindow() { delete this->overlay; }
+	virtual ~SmallMapWindow();
 
 	static void RebuildColourIndexIfNecessary();