add a tutorial and copy tutorial.html to crpp web, created page:...

add a tutorial and copy tutorial.html to crpp web, created page: http://crpp,epfl,ch/~sauter/gdat linked to this tutorial

git-svn-id: https://spcsvn.epfl.ch/repos/TCV/gdat/trunk@4880 d63d8f72-b253-0410-a779-e742ad2e26cf