add QAD::VirtualKeyboard library, vkbd for widgets with JSON-based description

libs/virtual_keyboard/plugin/qad_virtual_keyboard.h

@@ -0,0 +1,24 @@
+#ifndef qad_virtual_keyboard_h
+#define qad_virtual_keyboard_h
+
+#include <QtCore/qplugin.h>
+#include <QtDesigner/QtDesigner>
+
+class QADVirtualKeyboard
+	: public QObject
+	, public QDesignerCustomWidgetCollectionInterface {
+	Q_OBJECT
+#if QT_VERSION >= 0x050000
+	Q_PLUGIN_METADATA(IID "qad.virtual_keyboard")
+#endif
+	Q_INTERFACES(QDesignerCustomWidgetCollectionInterface)
+
+public:
+	explicit QADVirtualKeyboard(QObject * parent = 0);
+	virtual QList<QDesignerCustomWidgetInterface *> customWidgets() const;
+
+private:
+	QList<QDesignerCustomWidgetInterface *> m_widgets;
+};
+
+#endif