Readded NdElement interface for backward compatibility
Readded NdElement interface for backward compatibility

basnijholt/holoviews,ioam/holoviews,vascotenner/holoviews,vascotenner/holoviews,basnijholt/holoviews,basnijholt/holoviews,ioam/holoviews,ioam/holoviews,vascotenner/holoviews