Remove the Fortran high-level interface

This removes the untested and seemingly unused Fortran high-level interface and the elements of build systems that support it.

doc/libmtime.dox

@@ -94,9 +94,3 @@ SPDX-License-Identifier: CC0-1.0
 *
 * This module documents the Fortran language bindings
 */
-
-/** @defgroup FortranHLBindings libmtime high-level Fortran language bindings
-* @ingroup libmtime
-*
-* This module documents the high-level Fortran language bindings
-*/