Generator or Stream should define hasNext (can leverage atEnd) so they can be used with AsyncIteratorStream

[botwhytho]

By defining Generator>>#hasNext, one can use that class to feed an async stream.

Something like below on the class hierarchy would be useful

hasNext
	^ self atEnd not

Some example code that makes use of Generator after that change was added locally.

nums := 1 to: 42.
counter := 0.
generator := Generator
		on: [ :gen | 
			[ counter := counter + 1.
			gen yield: (nums atWrap: counter) ] repeat ].
list := BrSimpleList new
		itemStencil: [ BrLabel new
				aptitude: BrGlamorousLabelAptitude new
						+ (BrStyleCommonAptitude new
								selected: [ :aStyle | aStyle background: Color veryVeryLightGray ]);
				padding: (BlInsets all: 5) ];
		itemDataBinder: [ :eachElement :eachInteger :eachIndex | eachElement text: eachInteger asString ];
		stream: (AsyncIteratorStream forIterator: generator)