include rx headers earlier
missing return in maybe
implement AsyncSubject and ToAsync
implement FromAsyncPattern
use FromAsyncPattern to make ReactiveSave from SaveAsync
use ReactiveSave when the app is suspending
implement publish and refcount

ConnectableObservable, ConnectableSubject and Multicast were
prerequisits for publish and recount. all are implemented here.
fix for ScheduledObserver
remove excessive semi-colons
fix windows include guard
fix winrt include guard
Adds many new operators and some bug fixes

- Producer and Sink helpers
- Return
- Using
- New RefCount impl
- ConnectForever
- Scan
adds ReactiveCommand and BindCommand
Use ReactiveCommand in all 3 scenarios