Change x_x_than_single consistency checks from 4 variants to 3

[intarga]

There seem to really be 3 possible climate relationships here. Either the single value should be above all in the sequence, within the range of the sequence, or below all. In this sense there is some overlap in the meaning of min_greater_than_single and max_less_than_single. Perhaps these should be combined into one test called single_outside_sequence?