update the CI configuration; prep for publishing (#44)

stable null safety release (#34)

clean up some apis (#30)

- drop support for Uri objects in DirectoryDescriptor.load
- Use Object? instead of dynamic for `FileDescriptor` contents parameter
- Remove `parents` param in DirectoryDescriptor.load

Add an archive descriptor (#21)

Add helpers to make it easier to do stuff in the sandbox (#13)

Merge pull request #14 from dart-lang/test-update

Support test 1.x.x

Remove comment-based generic syntax.

Declare support for async 2.0.0.

Bug fixes.