Renamed Compositor._collapse to collapse_element
Renamed Compositor._collapse to collapse_element

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