This commit fixes the following issues around the way comparisions are
merged with ranges in conjunctions:
* the decision to include the equality of the lower limit is corrected;
* the selection of the upper limit is corrected to use the upper bound
of the range;
* the list of terms in the conjunction is sorted to have the ranges at
the bottom; this allows subsequent binary comarisions to find compatible
ranges and potentially be merged away. The end guarantee being that the
optimisation takes place irrespective of the order of the conjunction
terms in the statement.

Some comments are also corrected.

Replace anonymous comparator of split AND Expressions with a lambda.