TODO

IMPORTANT: Every world process may not use a set as an ETS Table, otherwise, same latitutdes will collide with each other
todo: add unkown message tests
todo: fix bug at shutdown
todo: build a cascading pausing system: if a state is pausing, the message "pausing" is returned and the process switches to the mode "pausing" automatically.
      only when all processes are in the pausing mode, they are set to "paused" by the world server.
todo: correct the restart strategy to add connections
todo: write a design document
todo: infectedpopulation must be set in the config file
todo: rework everything
todo: use exceptions