remove continuation manually if terminated by not being assigned

update changelog

make unwrappedStream public

Added unwrappedStream() method to AsyncObservable that allows you to …

…read a stream of only non-nil values when the type is Optional.

- I changed the API because I like to use the word value in other par…

…ts of my code and I ended up using value.value and it made me sad.

  - value -> raw
  - valueObservable -> observable
  - valueStream -> stream

Add AsyncObservableReadOnly

If you want to expose an AsyncObservable as a read only property, you can use the AsyncObservableReadOnly protocol externally.

class SomeClass {
  // .update is availble on the private property
  private let _someProperty = AsyncObservable(whatever)
  // but not on the public property, unless someone casts, but this should be enought of a deterrent
  var someProperty: AsyncObservableReadOnly<String> { _someProperty }
}

Update readme

Add documentation