Added seller interface for preparing shop items from other plugins.

shop/iseller.h

@@ -0,0 +1,22 @@
+#ifndef ISELLER_H
+#define ISELLER_H
+
+#include <QObject>
+
+#include "ishopitem.h"
+#include "shop_global.h"
+
+class SHOPSHARED_EXPORT ISeller : public QObject
+{
+    Q_OBJECT
+public:
+    explicit ISeller(QObject *parent = 0);
+    virtual ~ISeller();
+
+    virtual void prepareItem() = 0;
+
+signals:
+    void itemPrepared(QSharedPointer<IShopItem> item, int count);
+};
+
+#endif // ISELLER_H