Add: new method for NamedQueue
Add: there is new concept of effect

Brief explanation. Calendar has events, events can cause effects or
actions. Actions are spawned by events, they may cause effects or
actions. Effect is just applied. Actions and events have attribute
'events' and 'effects' that should be accessed by getter 'get_effects'
and 'get_events'. If events needs to do something more than cause effect
or action there is method __call__ that can be overriden. Also both
effects and actions may put additional events to calendar by standard
means, that is accessing calendar instance and executing method
add_event.
Change: outcome was scrapped, new effect file was added
Change: simplified rather complex if clause
Add: sovereign can be dead, if it's true game is over