Fix issue where calibration wasn't updated if guider binning was changed

Calibration is done with a particular binning. The user may change binning when running the guider, but previously the guide calibration was not updated to reflect the new binning, and thus generated wrong results (e.g. the number of arc-seconds per pixel would reflect the binning used in calibration, not the binning in current use).

This is a real bug, and should be fixed, and definitely affects folks that might change guider binning, so I set milestone 3.5.5. However, I also suppose that this is a long-standing bug and just was just discovered, so it's also possible to slip it to 3.5.6 as well.

Coded, passes unit tests, but needs some real-telescope testing.