Canvascli

Added
- Warn when there are ungraded assignments, similar to the warning for unposted assignments.

Fixed
- Show less rows and columns in warnings to make the output easier to overview.
- Fix numexpr issue with macs not being able to use the C engine for pandas query

Fixed
- Switch to check "creation" instead of "start" date in the `show-courses` subcommand,
since many courses don't have a "start" date listed.
- Fix handling of NAs in date strings for `show-courses` subcommand.
- Check that all necessary fields exist and raise an informative error if they do not.

Fixed
- Fix regression introduced in 0.6.0 where the checking for the student id was done incorrectly so that it always evaluated to False.

Added
- Automatically detect if there are multiple sections and display a boxplot for each section automatically.
- Include an option flag to include whether to group by section, grader, or nothing for the charts.
- Add search box to filter students names in the charts.
- Add percentile information to each student in the hover info in the scatter plot.
- Show progress bar while downloading grades
- Check for students being part of multiple sections.

Changed
- Use boxplots with hover info (count, mean, median, quartiles) instead of just a marker for mean and median. Useful to report both overall stats and for each assignment/quiz.
- Extract student specific section ID instead of propagating the same ID to all students. Useful for courses with combined sections on Canvas.
- Lay out the scatterplot as a violin cloud so that it is easier to tell the shape of the distribution and the layout is deterministic when changing the dropdown menu or filtering via the search box.
- Prompt for inclusion of assignments and make the regex easier to use.
- Change the default number of histogram bins and the range to be more suitable for most grading scenarios.

Fixed
- Adjust position of text and widgets to make the charts clearer.
- Support missing student numbers (happens with concluded courses).
- Support section IDs that are not numeric
- Align scales and ticks between boxplots and histograms.

Changed
- Remove placeholder commands that have been implemented as part of viz already.

Added
- Visualize individual student assignment scores.
- This makes it possible to see how a student is doing over time
and if intervention is needed.
- Optionally filter how many assignments show up in the visualization.
- Link Final Grade Plot with individual student assignment scores.
- Visualize score distributions for each assignment along with mean and median.
- Visualize a comparison between scores from each grader.
- Center chart titles and add more elaborate instructions.
- Show mean and median grade in plot.

Changed
- Require Python 3.8 instead of 3.6 to ensure that importlib.metadata is in stdlib.
- Make saved messages stand out and simplify final info note.
- Make hover highlighting more intuitive and better explained.
- Filter out unpublished assignment and those missing a max score.
- Put assignment titles on top of plots instead of to the left.
- Maintain assignment order from Canvas in all visualizations.
- Only show a sample of the students with unposted assignments.

Fixed
- Make rounding work with dfs containing None instead of NaN
(happens when all values are None for an assignment and there is no type casting)