Initial implementation of glabels-batch.

Note: must currently use QGuiApplication instead of QCoreApplication to
support QFont.  Unfortunately, this means that glabels-batch must run
within a windowing system.  Ideally, it would not have this requirement.

glabels/Db.cpp

@@ -430,7 +430,6 @@ namespace glabels
 	{
 		if ( !isTemplateKnown( tmplate->brand(), tmplate->part() ) )
 		{
-			tmplate->initPreview();
 			mTemplates << tmplate;
 		}
 		else