Remove secret F6 refresh key

Not needed as all non-refresh bugs seem to be squashed now.

mainwidget.cpp

@@ -362,11 +362,6 @@ void TeletextWidget::keyPressEvent(QKeyEvent *event)
 		case Qt::Key_PageDown:
 			m_teletextDocument->selectSubPagePrevious();
 			break;
-		case Qt::Key_F6:
-			m_pageDecode.decodePage();
-			m_pageRender.renderPage(true);
-			update();
-			break;
 		default:
 			QFrame::keyPressEvent(event);
 	}