Add a type ('change') to StateChange();
Fix specs
Add tokenAdded and tokenRemoved to history
Update historyEvent for added and removed tokens
Fix type handling in HistEvent of history
Add state listeners to artificialToken

This way aT can update its list also when something aT related is
coming from elsewhere (as from the history plugin).
Make history.silence public and refactor
Add history to sg conf
Honor maxSize in history
Fix formatting of historyList
Propagate handling of event silence to state