Add a shiny new event system
convert events to new style
ping: convert to new events
plugins: don't pass 'track' kwarg to register
plugins/monitor: convert to new events
plugins/script: make events wait for their script actions to complete
process: new event compatibility, better cooperation with ServerStart and ServerStopped
manager: new events
events: remove useless debugging feature from EventList
plugins/push: new events
plugins/backup: make things wait while ~backup is running