Draft Specification for V3

• Make all the conditions of state transitions customizable
  • Replace ReadyToTrip with ReadyToOpen
  • Add ReadyToClose to specify the condition of the transition from Half-Open to Close
  • Add ReadyToReopen to specify the condition of the transition from Half-Open to Open

type Settings struct {
	Name          string
	Interval      time.Duration
	Timeout       time.Duration
	ReadyToOpen   func(counts Counts) bool
	ReadyToClose  func(counts Counts) bool
	ReadyToReopen func(counts Counts) bool
	OnStateChange func(name string, from State, to State)
	IsSuccessful  func(err error) bool
}