Added optional PNG and SVG display hooks
Added optional PNG and SVG display hooks

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