Started by Perry; I will finish.

This was actually mostly done by the time Perry turned it over to me; I think the additional work I've done mostly falls into the category of "post-review changes", though in this case it's the reviewer who has made them rather than the original author (in the interest of getting this in quickly while Perry's away).

The one item that needed a lot more work is the example and task documentation for forced measurement, which I'll defer to a new issue.

So I'm going to consider this reviewed, and (in Perry's absence) merge it to master shortly.

Moving this back to "In Progress". After getting some comments from Perry via email about how he intended this to go, I'm going to take this approach:

• Move the addition of PeakLikelihoodFlux and ApertureFlux to branches for DM-446 and DM-837 (respectively).
• Remove the dependency this ticket has on ApertureFlux (i.e. don't use it in the examples).
• Finish DM-978, then rebase the pure-documentation stuff on top of that (otherwise there are big conflicts). I may split that into subtasks, with docs for SFM going on a different subtask issue than the docs for forced measurement.