Getting the master branch up-to-date with https://seiscode.iris.washington.edu/svn/emtf-fcu/trunk r30.

Includes several bug fixes of importance in some specific circumstances.

1. Many pointers are now nullified rather than deallocated to ensure compatibility with the latest
version of gfortran which gagged on those statements, causing segmentation faults.

2. A cleanup and an important bug fix for the computation of the error bars for EDI SPECTRA files.
While a general clean up has also been implemented, the only substantive change that involves a bug
fix relates to correct estimation of the residual covariances from single station SPECTRA.
There used to be a sign error that is now corrected. Unfortunately, this sign error has made its
way into the corresponding Geophysics paper https://doi.org/10.1190/geo2018-0679.1

3. Cleaned up the read of EDI files with *.EDI uppercase extension.