deal with same-model overlapping uploads

Ready for review @jh-bate @kentquirk 

I'd like to call out some of the changes in `carelinkDriver` in particular: we are now only dealing with rows of data that contain types that we actually use in our parsing. (There were all sorts of weird spurious overlaps going on with uploads with some of the other data types like `ResultDailyTotal` and `SensorTimestamp` that we don't read, but if I restricted it to data types we read, I was able to get around that.)

We also have to focus on rows containing insulin pump data, at least wrt detecting overlapping uploads. (Uploads from meters into Carelink are common but are almost guaranteed to overlap.) Right now I have a list of "supported models" in `removeOverlapping.js`. Alternatively we could maybe do this via regex; I'm not actually sure which is safer because there's a couple different perspectives from which to look at it...
what wrong with `i` :)