Added nearest neighbor indexing to Grid
Added nearest neighbor indexing to Grid

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