Fixed a bug in akgl_heap_next_string, made screen width and height load from properties, not on the game object

src/heap.c

@@ -98,6 +98,7 @@ akerr_ErrorContext *akgl_heap_next_string(akgl_String **dest)
 	    continue;
 	}
 	*dest = &HEAP_STRING[i];
+	HEAP_STRING[i].refcount += 1;
 	SUCCEED_RETURN(errctx);
     }
     FAIL_RETURN(errctx, AKERR_HEAP, "Unable to find unused string on the heap");