I was rethinking this while at the gym as well, but I think maybe an easier change (that could be done in short term) is to return the type of the data involved in the `breakdown` object that the bgUtil returns. Then the display code will just ask about the type where necessary, and it won't be necessary to track the "state" of whether we're using cbg or smbg for stats globally.

The handler pattern (with it including no data views) sounds like a great idea for down the road, thanks.