Upgrade Guideline from 3.x to 4.x

So far we have the following libraries we want to make a more detailed guidelines for:
- Database Class (Query Builder)
- Config Class
- Email Class
- Encryption Class
- File Uploading Class
- Input Class
- Loader Class
- Localization
- Output Class (HTTP Responses)
- Pagination
- Session Library
- Database Migrations
- Validation
- View Parser
- HTML Table Class
- Unit Testing Class

Do you have any libraries you would like us to add to our list?

Cheers,
Niklas