Enabled elFinder duplicate command. Also removed the function that wanted to play a sound every time a file was deleted (appeared in firebug)  according to this post: https://github.com/Studio-42/elFinder/issues/430

git-svn-id: http://voronet.francu.com/repos/DEX@918 8d550267-2627-4c68-899f-85492a8dd5ca