The idea here is that the ordering and algorithm for sorting are
two orthogonal parameters that have sensible defaults: neither,
both or either can be independently specified. The resulting API
is slightly more verbose but also somewhat more self-documenting.
Another sign that this might be on the right track is that this
change reduces the LOC of base/sort.jl by 41 lines and reduces the
method count of sort, for example, from 12 to 6.