Version filtering and general related code sanitization.

Version list dialog has alternating row background set.
Nostalgia versions, based on OneSix.

backend/NostalgiaInstance.cpp

@@ -0,0 +1,12 @@
+#include "NostalgiaInstance.h"
+
+NostalgiaInstance::NostalgiaInstance ( const QString& rootDir, SettingsObject* settings, QObject* parent )
+	: OneSixInstance ( rootDir, settings, parent )
+{
+	
+}
+
+/*
+ADD MORE
+  IF REQUIRED
+*/