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/ObjectStore.h

@@ -6,6 +6,10 @@
 #include "engine_build_config.h"
 #include "reusable_ids.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif // !__cplusplus
+
 typedef void (*EventHandlerPtr)(const SDL_Event *event, void *object);
 typedef void (*UpdateFuncPtr)(float delta, void *object);
 typedef void (*RenderFuncPtr)(void *object);
@@ -15,7 +19,7 @@ typedef struct object_store ObjectStore;
 ObjectStore *create_object_store();
 ObjectID add_object_to_store(ObjectStore *os, void *object, EventHandlerPtr eh,
                              UpdateFuncPtr uf, RenderFuncPtr rf);
-void remove_object_from_store(ObjectStore *os, ObjectID id);
+void remove_object_from_store(ObjectStore *os, ObjectID *id_ptr);
 void handle_all_objects_events(ObjectStore *os, const SDL_Event *event);
 void update_all_objects(ObjectStore *os, float delta);
 void render_all_objects(ObjectStore *os);
@@ -25,4 +29,8 @@ void destroy_object_store(ObjectStore *os);
 void print_objects(ObjectStore *os);
 #endif // !DEBUG_ENGINE
 
+#ifdef __cplusplus
+}
+#endif // !__cplusplus
+
 #endif // !OBJECT_STORE_H