project: (semantic) transition to foss21.org.
    
    Its development history notwithstanding, the pronounced goals of
    slibtools have always included support of all reasonably modern,
    reasonably posix-compliant systems and cross-targets. This commit
    thus makes the distinction between 'part of the midipix framework'
    and 'created by the framework's lead developer' both clearer and
    more visible.