Replace set[Plain]Text(QString()) with clear()

...where applicable. Shorter, faster, more semantic.

Change-Id: Ifb1cf200f489f62a79e12c761e98a846992744dc
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/coreplugin/dialogs/newdialog.cpp

@@ -429,7 +429,7 @@ void NewDialog::currentItemChanged(const QModelIndex &index)
         }
 
     } else {
-        m_ui->templateDescription->setText(QString());
+        m_ui->templateDescription->clear();
     }
     updateOkButton();
 }