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/qetapp.h

@@ -281,6 +281,7 @@ class QETApp : public QObject
 		void initSplashScreen();
 		void setSplashScreenStep(const QString & = QString());
 		void initLanguage();
+		void initFonts();
 		void initStyle();
 		void initConfiguration();
 		void initSystemTray();