* Make error handling optionally more permissive.
* Make the LanguageVersion be an object, not a string.
* Make it version 3.0.0-dev

* Allow nested packages.

Giving it the package name package_config_2 to avoid conflict with the existing package_config which is used by the `test` package.

This is the initial version. It will be updated to allow overlapping packages, as long as no file in the package URI root can be considered as belonging to a different package.

Fix missing_return violation newly enforced in Dart ~2.3.2-dev.0.1

Also fixed usage of deprecated matcher classes

bump sdk constraint to 3.0.0

Remove `strong`.

dart2 fixes

core api use migrations

Update .gitignore to new `dart_tool` pub cache

See: https://github.com/dart-lang/sdk/issues/32030

...instead of a String

Make trusty default distro explicit.

Update SDK constraint to be 2.0.0 dev friendly.