Add linear detrend and better bad data labeling
Add linear detrend and better bad data labeling

- [x] Add linear detrend and a linregress property giving various
      useful information related to the line of best fit.
- [x] Revamp interface for removing trend; rename `subtract_means`
      to `detrend` and give different values, with update to
      documentation.
- [x] Add a calculation of and plot label for the drift
      coefficient.
- [x] Make bad time markers show up above all other plot elements.

stefco/geco_data,stefco/geco_data,stefco/geco_data