Add %sort(), which binary-sorts a single list of values, and
%dribble_merge(), which takes a quoted length, a separator,
and some expressions and produces a list of lists of values
using the separator, where no list is larger than the length.

The schema declarations which we use for self-tests contain some syntax
errors that are flagged by newer versions of ns-slapd.  Fix them.

When checking if we can skip processing for a given change, pay
attention to whether or not the changes cause the entry to need to be
added or removed from a map (#912673).

Case sensitive comparisons keep getting tripped up by DN
canonicalization and the like.

  as literals