slides: move intro into its own directory

git-svn-id: http://svn.lal.in2p3.fr/projects/Enseignement/LAL-Info/trunk@3593 d5b9ce2a-b7ff-0310-b5dd-cb2f0fc3267d
slides/intro: 2013

git-svn-id: http://svn.lal.in2p3.fr/projects/Enseignement/LAL-Info/trunk@3594 d5b9ce2a-b7ff-0310-b5dd-cb2f0fc3267d
slides/cxx-io-stl: first import

git-svn-id: http://svn.lal.in2p3.fr/projects/Enseignement/LAL-Info/trunk@3595 d5b9ce2a-b7ff-0310-b5dd-cb2f0fc3267d
index: link to cxx-io-stl

git-svn-id: http://svn.lal.in2p3.fr/projects/Enseignement/LAL-Info/trunk@3596 d5b9ce2a-b7ff-0310-b5dd-cb2f0fc3267d