Add support for splitting an arbitrary number of arrays.
Add support for splitting an arbitrary number of arrays.

At the moment those arrays are hard coded, but they could eventually be
supplied as an argument to the function.

This functionality now means we can scale the physics data (mainl flux,
but also temperature and salinity) and the ERSEM variables if we're
using FVCOM-ERSEM.

pwcazenave/fvcom-toolbox,pwcazenave/fvcom-toolbox