Add Streams
Add Stream.with_index/1 and Enum.with_index/1
Add Stream.cycle/1
Improve Stream doctests
Deprecate File.*iterator! in favor of File.*lines_stream!
Improve the docs
Add Stream.reject/2 and Stream.(drop|take)*/2
Decide on IO.stream and unify read/readline API
Merge branch 'jv-streams'
Update CHANGELOG