Remove pubspec tasks from 'Dart' buid system

They are now in 'Dart - Pubspec'.
Fix bug
Refactor lib\path.py
Merge pull request #180 from my-personal-forks/pubspec

Pubspec
Merge pull request #178 from my-personal-forks/refactor

Refactor lib\path.py
Remove old video
Coerce error into string
Fix build script: Vintageous ==> Dart