GPA options panel update

Only reload DOM if toggling to visible
Hide GPA if result is NaN (e.g. no courses included)
Hide honors/regular toggles if gpa_weighted is false
Added header to GPA options panel
Aesthetic fixes

Centered assignment grades
Updated course average appearance
Grade edit tab navigation!
Merge commit '36471bc24e0d8cca9302bf945eb7fc4b3b30700a'