The SortOrder interface could support a reverse option?

[mbostock]

I was struggling to remember I needed to specify order: "descending" instead of reverse: true. Perhaps we could support both?

[mbostock]

The use of reverse: boolean in ChannelDomainOptions is confusing because it doesn’t mean (exactly) to reverse the order: it means to use descending natural order instead of ascending natural order. The difference is that descending natural order still puts null/unorderable values last, whereas reversing ascending natural order would put null/unorderable values first. Therefore it would probably make more sense to add a order option to the ChannelDomainOptions interface, and change the meaning of the reverse option so that it puts nulls first (assuming that you leave order as the default ascending). We could also allow the order option in ChannelDomainOptions to be specified as a comparator function.