The tutorials directories were reorganized.

Original:

public_html/
   GDE/
     tutorials


New:

public_html/
  tutorials/
      GDE/


As well, the symbolic link $birch/tutorials, which previously pointed
to public_html/GDE now points to public_html/tutorials.

A temporary symbolic link public_html/GDE --> tutorials/GDE
has been added. I think I already have changed all pages, both
on the BIRCH web site and on pages belonging to 'frist', but
we'll leave this link for awhile.

