SDLPP: add option to specify render object alignment

sdlpp/sdlpp_linerenderer.hpp

@@ -38,7 +38,6 @@ public:
     virtual int collisionWidth() override;
     virtual int collisionHeight() override;
     virtual void updateSizeAndPosition() override;
-    virtual void centerX() override;
     virtual std::shared_ptr< RenderObject > copySelf() override;
 
     virtual SDL_Rect getRect() override;
@@ -48,7 +47,7 @@ public:
 
 protected:
     virtual void copyTo( std::shared_ptr< RenderObject > other ) override;
-    void updateXY();
+    virtual void updateXY() override;
     Line< double > original = { { 0, 0 }, { 0, 0 } };
     Line< double > current = { { 0, 0 }, { 0, 0 } };
     Line< int > pixel_line = { { 0, 0 }, { 0, 0 } };