Add doc comment on Stream.slices (#180)

Based on the doc comment on the unmerged Iterable.slices from
https://github.com/dart-lang/collection/pull/191

Drop extra newline in changelog, sort deps, and drop `-nullsafety` from
constraints.
3 files changed
tree: b92a23bc4070239d130a49f0d03a5cc033e09d71
  1. .github/
  2. lib/
  3. test/
  4. .gitignore
  5. AUTHORS
  6. CHANGELOG.md
  7. CONTRIBUTING.md
  8. LICENSE
  9. README.md
  10. analysis_options.yaml
  11. pubspec.yaml
README.md

Contains utility classes in the style of dart:async to work with asynchronous computations.