Return visit-level MCAT sources when trange is passed to gFind.

[cmillion]

The current functionality returns the "coadd" catalog values as a method of checking for nearby contaminating sources or maybe re-centering the search or aperture. Because a lot of the time we want to compare gAperture photometry to the MCAT photometry or look for nearby sources that were simultaneously observed (e.g. to look for field-wide systematics due to the observing mode or pattern), it would be useful to have the visit-level MCAT data in these case.

The functionality should be changed so that if trange is passed to gFind, it will search the MCAT for visits that fall within or overlap the requested time range and return those instead.