Add support for the three hourly output data for the 19.0 and 19.1 experiments.
Add support for the three hourly output data for the 19.0 and 19.1 experiments.

The change enables downloading of the three-hourly data from the HYCOM
+ NCODA Global 1/12 degree Reanalysis. In order to maintain backwards
compatibility, this change must be enabled with a new keyword-parameter
pair (`three', [true/false]). It defaults to the existing behaviour of
only downloading the data at midnight each day.

pwcazenave/fvcom-toolbox,pwcazenave/fvcom-toolbox