GUI: add CLI equivalent dialog (#163); use spinboxes in Sequence dialog

and restrict sequence to max 10,000, add button icons;
   make Export dialog sizable and show every 100 results, add button icon;
   fix saving CHANNEL option, fix Export painting main window (Windows), fix
   guard descent not-resetting
 qzint: add getAsCLI(), warnLevel(), extra isStackable()/isComposite() etc
 Add ZBarcode_BarcodeName()
 manual: doc above, some fixes, tweaks

frontend_qt/barcodeitem.h

@@ -31,6 +31,7 @@ class BarcodeItem : public QGraphicsItem
 public:
     BarcodeItem();
     ~BarcodeItem();
+
     void setSize(int width, int height);
     QRectF boundingRect() const;
     void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0);