Determines the parameter name for a default contrast of a non-reference level against
the reference level: the second factor level is trt, the third trt_alt2, the fourth
trt_alt3, and so on. Only used for the default (group_contrasts = NULL) set;
user-supplied contrasts are named explicitly by the caller.
ancova_contrast_name(i, labels)A length 1 character vector with the parameter name.
Integer, 1-based index of the (non-reference) group level.
Character vector of level labels as returned by ancova_group_labels().