Tabulator and Plotly improvements

[Ruborcalor]

Improvements such as:

• Preventing unwanted scrolling on assignments table edit
• Adding assignment filtering via the categories table
• Redirecting to grades page when clicking on recent activity table

[Ruborcalor]

Improvements such as:

• Boxplot rounding correction
• Boxplot mean identification via line
• Boxplot annotations for "Mean" and "Your Score"

[maxtkc]

Looks great!

Two small possible additions for when an assignment is clicked in the recent activity table:

• Select the Grades tab as if it was clicked
• Select the class row corresponding to the clicked assignment

Also, a super quick fix:

• When categories are selected, use the blue row select builtin to tabular (same as the classes table)

And styling stuff for Boxplot:

• Make Your Score easier to see than Mean (swap colors of the two lines, make the text bigger/colored and in the same font as the page)

Feel free to nix any of these if you disagree.

Other than that, it looks ready to merge!

[Ruborcalor]

More Improvements:

• Improve positioning of "Your Score" and "Mean" annotations so that their positions are dependent on screen width. This will ensure that they aren't cut off. (Or find way to not cut them off)
• Add trace that divides plot into letter grades