Date fields can now be updated and their values retrieved. So now I have added a button that retrieves the range of the date field and updates the historical view in response to them.
This sets up a bunch of callbacks. We're starting to get into Callback Hell, where there are things that need knowledge that I really don't want them to have.
However, edit fields for TimeDistanceEdit now propogate data back into the view model, which is then able to save the results.
I move the weight edit view into the validated text entry widget, and I
work on some of the unfortunate logic in the weight blur function. I've
left behind a lot of breadcrumbs for things that still need to be done.
