Include some fonts to QElectroTech

- include Liberation-Fonts and osifont
  (thanks elevatormind!)
- use "Liberation Sans" as default-font
- adjust License-Tab in About-Form
- Bugfix: When selecting a font, the current
  font is highlighted in dialog
- adjust some whitespace and English comments

sources/qet.h

@@ -28,7 +28,8 @@ class QActionGroup;
 	anywhere else within the QElectroTech application.
 */
 namespace QET {
-	QString license();
+	QString license();  // only QETs license
+	std::tuple<QString, QString> licenses(const QString &); // all licenses
 	
 		//Describe the current state of a graphic item
 	enum GraphicsItemState {