/// \return the layout object of an inset given by name. If the name
/// is not found as such, the part after the ':' is stripped off, and
/// searched again. In this way, an error fallback can be provided:
/// \return the layout object of an inset given by name. If the name
/// is not found as such, the part after the ':' is stripped off, and
/// searched again. In this way, an error fallback can be provided: