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

src/IndexTexture.h

@@ -0,0 +1,11 @@
+#pragma once
+#include "Common.h"
+class GameEngine; // forward declare
+
+class IndexTexture {
+public:
+    sf::Texture texture;
+    int grid_size, grid_width, grid_height;
+    static GameEngine* game;
+    sf::IntRect spriteCoordinates(int);
+};