Use a new context for every new created component.

This is fixing many crashes but maybe not anymore in line with the qml
viewer.

Task-Number: BAUHAUS-622
Reviewed-by: kkoehne

src/plugins/qmldesigner/core/metainfo/nodemetainfo.cpp

@@ -176,7 +176,7 @@ QObject *NodeMetaInfo::createInstance(QDeclarativeContext *context) const
         // qml component
         // TODO: This is maybe expensive ...
         QDeclarativeComponent component(context->engine(), QUrl::fromLocalFile(m_data->qmlFile));
-        object = component.create(context);
+        object = component.create(new QDeclarativeContext(context));
     } else {
         // primitive
         object = QDeclarativeMetaType::qmlType(typeName().toAscii(), minorVersion(), majorVersion())->create();