Sort the Exercise Analytics by location in the chapter

[sahi1l]

Describe the bug
The circle graphs for the different problems are displayed in (as far as I can tell) completely random order, which is very frustrating and makes it hard to correlate with the Overall Progression bar graphs above it. If at all possible, please sort the circle graphs in order of appearance in the book, or at least alphabetically.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://runestone.academy/runestone/dashboard/index?chapter=Iteration
2. Scroll down to Exercise Analytics
3. Note that the first circle is question6_6_1, which is from section 6 of Chapter 7, and the circle to its right is question6_5_2 from section 5.

Expected behavior
That the circles be listed in order of appearance in the textbook, preferably left-to-right and then top-to-bottom, but the reverse if necessary.

Bonus feature suggestion
Give the user the ability to sort the circles alphabetically, by appearance, by completion percentage, and so forth.