Split log_run into start_run and finish_run. Added some extra functions to provide info on logged and active runs.
Added logged_runs as "option" to make saving the log a bit simpler.
Added missing scheduling functions. check_schedule function is now available to activate outputs according to schedule. This includes activating the master station when needed. Rain sensor has still to be taken into account.
Made all classes, that should not be created by other modules, protected.