D.8.4 Additional harminv notes

The harminv library interface requires the harminv and lapack libraries to be installed on the host system, and also requires standard complex number support from the system's C library.

The author's installation of avram has been compiled against the Debian harminv development library package, which at this writing is unmaintained and is missing the necessary header file harminv-int.h, without which compilation of files including harminv.h fails. Some headers from harminv.h have been copied directly into avram-x.x.x/src/harminv.c under the avram source tree to avoid this dependence, so that avram will compile correctly on a Debian system. These may need to be updated if necessary to track the harminv source.