longitudeTighten shifts some longitudes in its first argument by 360 degrees, if doing so will reduce the overall longitude span.
longitudeTighten(section)A '>section object based on its first argument, but with
longitudes shifted in its metadata slot, and also in the metadata slots
of each of the '>ctd objects that are stored in the station item
in its data slot.
This function can be helpful in cases where the CTD stations within a section
cross the cut point of the longitude convention, which otherwise might
yield ugly plots if plot,section-method() is used with xtype="longitude".
This problem does occur with CTD objects ordered by time of sampling,
but was observed in December 2020 for a GO-SHIPS dataset downloaded from
https://cchdo.ucsd.edu/data/15757/a10_1992_ct1.