Enabled SDL_image's support for PNG and TIFF files and improved the

AssetManager with a hashing function, a linked list structure to store
the hashes as well as a reference counter to support multiple users
sharing the same asset.

include/Window.h

@@ -6,6 +6,10 @@
 #include "SDL_pixels.h"
 #include <stdbool.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif // !__cplusplus
+
 typedef struct window {
   int width;
   int height;
@@ -20,4 +24,8 @@ void clear_window(const Window *wnd);
 void swap_render_buffers(const Window *wnd);
 void destroy_window(Window *wnd);
 
+#ifdef __cplusplus
+}
+#endif // !__cplusplus
+
 #endif // !WINDOW_H