new Italian translation (thanks Mattia)

git-svn-id: http://svn.code.sf.net/p/texstudio/code@4155 92cce386-e96d-4106-809f-596c673a3fd8
mention Italian translation on homepage

git-svn-id: http://svn.code.sf.net/p/texstudio/code@4156 92cce386-e96d-4106-809f-596c673a3fd8