Another checkpoint. Compiling/building/running - Python API tests from in-engine REPL are not passing, though

src/IndexSprite.h

@@ -0,0 +1,10 @@
+#pragma once
+#include "Common.h"
+class GameEngine; // forward declare
+
+class IndexSprite {
+public:
+    int texture_index, sprite_index, x, y;
+    static GameEngine* game;
+    sf::Sprite drawable();
+};