Fix: move class to class directory

htdocs/admin/project.php

htdocs/html.formother.class.php

htdocs/includes/modules/project/pdf/pdf_baleine.modules.php

htdocs/projet/activity/index.php

htdocs/projet/activity/list.php

htdocs/projet/class/task.class.php

htdocs/projet/tasks/contact.php

htdocs/projet/tasks/document.php

htdocs/projet/tasks/fiche.php

htdocs/projet/tasks/index.php

htdocs/projet/tasks/note.php

htdocs/projet/tasks/task.php

htdocs/projet/tasks/time.php