Add scheduleAfter methods
Add Observable.interval
Add ignore() over Streams
Add Stream.scan
Add Stream.combinePrevious
Add nub() over Streams
Add AsyncSequence.doEvent

This isn’t appropriate for Observable, since side effects can be
“injected” with a new subscription, which should be basically the same
thing.
Fix definition of scan()
Add Stream.aggregate
Add Observable.delay
Add Observable.deliverOn
Add Stream.ignoreValues
Add ! over Stream<Bool>
Add Observable.combineLatestWith
Merge pull request #14 from jspahrsummers/moar-operators

All the operators