Observers

This set of mixins is built around the Observer APIs and custom events to enhance your controllers with new behaviors.

Mixin	Description	NEW Callbacks
`useClickOutside`	Tracks the clicks outside of the element and adds a new lifecycle callback clickOutside.	`clickOutside`
`useHover`	Tracks the user's mouse movements over an element and adds mouseEnter and mouseLeave callbacks to your controller.	`mouseEnter` `mouseLeave`
`useIdle`	Tracks if the user is idle on your page and adds away and back callbacks to your controller.	`away` `back`
`useIntersection`	Tracks the element's intersection and adds appear, disappear callbacks to your controller.	`appear` `disappear`
`useMutation`	Tracks mutations on an element, its attributes and/or subtree. Adds a mutate callback to your controller.	`mutate`
`useResize`	Tracks the element's size and adds a new lifecycle callback resize.	`resize`
`useTargetMutation`	Tracks when targets are added or removed from the controller's scope, or their contents changed. Adds [target]TargetAdded , [target]TargetRemoved and [target]TargetChanged callback to your controller for each specified target.	`[target]TargetAdded` `[target]TargetRemoved` `[target]TargetChanged`
`useVisibility`	Tracks the page visibility and adds visible, invisible callbacks to your controller.	`visible` `invisible`
`useWindowResize`	Tracks the size of the `window` object and adds a new lifecycle callback windowResize.	`windowResize`

Observers #