Aded support for downloading hillshading DEMs

src/map/imgmap.h

@@ -74,6 +74,8 @@ public:
 	  bool hidpi);
 	void unload();
 
+	bool usesDEM() const {return true;}
+
 	bool isValid() const {return _valid;}
 	QString errorString() const {return _errorString;}
 

src/map/map.h

@@ -57,6 +57,7 @@ public:
 	virtual void draw(QPainter *painter, const QRectF &rect, Flags flags) = 0;
 
 	virtual void clearCache() {}
+	virtual bool usesDEM() const {return false;}
 
 signals:
 	void tilesLoaded();

src/map/mapsforgemap.h

@@ -71,6 +71,8 @@ public:
 
 	void draw(QPainter *painter, const QRectF &rect, Flags flags);
 
+	bool usesDEM() const {return true;}
+
 	bool isValid() const {return _data.isValid();}
 	QString errorString() const {return _data.errorString();}