Better BCA GPA

Adds several very useful features to PowerSchool.

Please submit all your feedback to this form: https://forms.gle/69qtRqJASghZQyhU7

In this current version, the following features are available:
- Add imaginary grades, and see how your final grade for a class would change.
- See accurate point values for all your class grades, down to the 4th decimal place
- Stylize the PowerSchool page to make it look better
- Quality of life PowerSchool changes
- Bug fixes

All features work for all classes, including classes using category weighting.

A GPA-related feature is coming soon. Stay tuned!