1.0.0 Beta 2

• Pipeline back-pressure has been modified to be relieved immediately when the value is consumed from the pipeline. Prior, another value had to be requested from the pipeline before back-pressure was relieved.
• Removed AsyncGenerator class. Instead, fromIterable now also accepts a Closure returning an iterable, which can be a generator function.
• concurrentOrdered has been removed and concurrentUnordered renamed to concurrent. Unfortunately, ordered iteration broke if using operators that would not always emit a value, so support has been dropped.
• Added an optional $bufferSize parameter to the Emitter constructor that sets a number of items that can be emitted before awaiting back-pressure from the pipeline consumer. This value defaults to 0, which will await back-pressure with every emitted value.