Update distribution design models directory structure. The schema
    Distro/$RELEASE/Component makes rendition difficult to control through
    FLAG_FILTER. There are two nested loops (one to load pre-rendition
    configuration scripts and other to load design models related to the
    pre-rendition previously loaded) and we need to deside which one of
    them does use the FLAG_FILTER.
    
        - If we use FLAG_FILTER to customize the first loop (the one
          loading pre-rendition configuration scripts) the best we can
          customize is which component is rendered but not which file
          inside the component because that is controlled by the second
          loop.
    
        - If we use FLAG_FILTER  to customize the second loop (the one
          loading design models, related to previously loaded
          pre-rendition configuration scrtip), the best we can do is
          customize which file names inside all components will be
          rendered, but not which file in which component.
    
        - If we use FLAG_FILTER in obth first and second loop makes no
          much useful thing. In this case, we are trying to apply a common
          search pattern to two different path informations which probably
          get in conflict one another since the regular expression pattern
          point of view.
    
    So, go back to the previous configuration where release and
    architecture information are set at the end of the path (e.g.,
    Distro/Component/$RELEASE).
    
    Another point of this configuration is that release-specific
    information can be supplied by means of `--release' option. There is
    no need to have one release-specific directory inside design models to
    produce design models on different artistic motifs. Nevertheless it
    could be required if file names, of files produced, change from one
    major release to another; or maybe not, since a tune up script could
    be set to fix the name issue or something similar.