rc 0.2.0

Dart environment variables for runtime configuration, `Platform.environment` wrapper.

0.2.0

Current version is incompatible of previous version.

0.1.0

• Remove package:rc/io.dart
• Add RuntimeConfiguration.from factory constructor
• Add all to getter
• Removed load method, now create RuntimeConfiguration will be resolved immediately

0.0.2

Fix child replace throw error

0.0.1

• Change Dart SDK min version to 2.17.0

0.0.0

• Initial version.