Add `debounce` utilities and prepare for publish (dart-lang/stream_transform#3)

- Add `debounce` and `debounceBuffer` to drop or collect values that
  occur quickly
- Add tests
- Drop `-dev` from pubspec to prepare for publishing very early version
- Add LICENSE file
- Exclude dartanalyzer and dartfmt test from 1.22.1 SDK
7 files changed
tree: 802ee129b97e8e3f08cc7ea484e067bbe01dae3f
  1. pkgs/