Retrieve and report per-board temps and voltages.

We should be retrieving and reporting the per-board temps and voltages. The HouseKeeping commands does that, but also returns per-cobra information which may or may not be useful. As it stands, fetching/parsing/checking HK for all 84 boards takes ~4.5s. Probably fine if we disable checks during convergence and motor maps. Might be worth seeing if we can pick up some easy gains in the processing.

Adding a board HK command would actually be pretty easy: we would just be disabling the per-cobra checks.

As far as STS, etc. goes, it is not clear that we really want the simple 168 or 252 channels. Maybe a summary of all the boards, or of the 6 sectors?