store only one direction of sprites

src/Entity.h

@@ -30,9 +30,13 @@ public:
   virtual const std::vector<std::string> &getMask() const = 0;
   virtual char getDefaultColor() const noexcept = 0;
 
-  virtual bool shouldBeRemoved() const noexcept = 0;
+  virtual bool shouldBeRemoved() const noexcept;
   virtual std::unique_ptr<Entity> createReplacement() const { return nullptr; }
   virtual int getPreferredLayer() const noexcept = 0;
 
   void draw() const;
+
+protected:
+  // Helper function to get the maximum width of any row in an image
+  static size_t getMaxRowWidth(const std::vector<std::string> &image) noexcept;
 };