DECODR interpolation routine changed significantly

In order to use the datacodes to control which values are used in an interpolation, the 'terple' routine was switched from row-oriented to col-oriented. Instead of starting at surface and going to terminal depth, the routine starts with a particular datatype, say salts, then interpolates standard depth values for that column. Using the data codes as criteria on which salt values to use. This is a significant change from the legacy terple routine which was changed from quadratic interpolation to linear interpolation and now col-oriented vs row-oriented.