revsetbenchmarks: clean up revsets that achieved with default variants We remove revset making use of min and max as this is covered by the variants. We could use variant for roots too, but it is not in the default so keep it here.

revsetbenchmarks: use combination variants in default set Now that we have them, let's make use of them.

revsetbenchmarks: support combining variants with "+" We need more advanced variants in some cases. For example, "The last rev of the sorted version". We introduce a syntax for this: `reverse+last` means `last(reverse(REVSET))`.