add settings icon,

set ogl verison to 2.0 to make it compatible with more PCs

QtMeshViewer/Resources/StyleSheet.txt

@@ -71,6 +71,10 @@ QToolButton#light:checked {
 	image: url(:/images/toolbar/light_on.png);
 }
 
+QToolButton#settings {
+	image: url(:/images/toolbar/settings.png);
+}
+
 QToolButton#fileInfo {
 	image: url(:/images/toolbar/info.png);
 }