Fix VC2013 warnings

oxygine/src/Sprite.h

@@ -42,8 +42,8 @@ namespace oxygine
 
         bool                    isOn(const Vector2& localPosition);
         
-        bool                    isFlippedX() const {return _flags & flag_flipX;}
-        bool                    isFlippedY() const {return _flags & flag_flipY;}
+        bool                    isFlippedX() const {return (_flags & flag_flipX) != 0;}
+        bool                    isFlippedY() const {return (_flags & flag_flipY) != 0;}
         void                    setFlippedX(bool flippedX);
         void                    setFlippedY(bool flippedY);
         void                    setFlipped(bool flippedX, bool flippedY);