Added __hash__ to Dimension and fixed eq and le
Added __hash__ to Dimension and fixed eq and le

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