Added a .md suffix to INSTALL, NEWS and TODO

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/EtoileFoundation@10562 7b3f36aa-e6db-49c1-8b4c-66eac1997e64
Updated references to TODO, NEWS and INSTALL

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/EtoileFoundation@10563 7b3f36aa-e6db-49c1-8b4c-66eac1997e64