Teigha克隆db的blockTableRecord里面的一个实体

    std::vector<OdDbEntityPtr> entities;
    OdDbBlockTableRecordPtr blkTblRcd = blockId.openObject();
    OdDbIdMappingPtr idMap = OdDbIdMapping::createObject();
    idMap->setDestDb(db);
    for (auto entIter = blkTblRcd->newIterator(); !entIter->done(); entIter->step())
    {
        OdDbEntityPtr pEnt = entIter->entity(OdDb::kForWrite);
        OdDbEntityPtr tempEntity = pEnt->deepClone(*idMap, pEnt);
        entities.emplace_back(tempEntity);
    }
    return entities;