SN_READSHIPMET - reads SIO ships MET data files
SN_READSHIPMET(FILENAME) returns a MET structure of variables described for MET data files
SN_READSHIPMET(DIRNAME) reads all *.MET files in the directory DIRNAME
SN_READSHIPMET({FILE1, FILE2,...}) reads all files indicated
Created 2012/03/30 San Nguyen
Updated 2012/06/09 San Nguyen - updated to read MET data for most ships not just the ones on the R/V Revelle
Updated 2015/09/02 San Nguyen - update to combine MET data without losing any fields added later on
Updated 2016/10/19 Emily Shroyer- Corrected Reanme Information
Updated 2016/10/20 San Nguyen - Update to read MET files in the same folder to preserve maximum number of fields that might have been added after the initial recording, not restricting number of fields to defined by the first file.