actors do share environment
added implementation for DefaultActor
fields are created at the beginning of the program, when world is initialized
lake is applying its world's rule (which field is lake)
by random process free_fields are being assigned to the actors by their type
free_land_field -> to land actors and bird
free_water_field -> to water actors
added asserting changes to clisp...working on loop
launching per request
did some changes...need further assistance from fellows to make it work...