Various extensions for references

[PlugFox]

• https://github.com/huang12zheng/Dart-Data-Class-Generator
• https://github.com/Flutterando/flutter-coverage
• https://github.com/hiranthar/Json-to-Dart-Model
• https://github.com/itmarck/flutter-tree
• https://github.com/Mastersam07/dart-print
• https://github.com/mikededo/dartBarrelFileGenerator
• https://github.com/localizely/flutter-intl-vscode
• https://github.com/lsaudon/l10nization