add had_entity_with_entity_id
add Board.delete_entity_msg and ut
switches to use the "entity_type" value string to directly store the class name
add add_new_entity_obj_using_existing_entity_id and add_entity_obj_with_new_entity_msg
run_tests now uses py.sh
add RealBoardCreationTest; deprecating unit_type property, use entity_type directly instead; add tile.ascii and Tile class; fix ut
correct the checking for unit type in Unit.__init__