refactored onMove and onDelete to view modifiers

- Dramatically simplified implementation and API (take a look at the …

…migration notes in the readme)

- AdvancedList is now more like the List and ForEach SwiftUI view

implemented move, delete and filter support

added tvOS 13 support

- refactored isLoading to state (error, idle and loading with a corre…

…sponding view)

- error and loading view are not part of the List anymore, now the List and the pagination state view (error or loading) are in a VStack