0.6.15

• New Feature
  • Observable
    • add toTaskOption (@mlegenhausen)
  • ReaderObservable
    • add toReaderTaskOption (@mlegenhausen)
• Bug Fix
  • Observable
    • prevent toTask from resolving to undefined on an empty Observable (@mlegenhausen)
  • ObservableEither
    • prevent toTask from resolving to undefined on an empty Observable (@mlegenhausen)
  • ObservableThese
    • prevent toTask from resolving to undefined on an empty Observable (@mlegenhausen)
  • ReaderObservable
    • prevent toReaderTask from resolving to undefined on an empty Observable (@mlegenhausen)