fn sorted_novel_positions(
    lhs_mps: &[MatchedPos],
    rhs_mps: &[MatchedPos],
    opposite_to_lhs: &HashMap<LineNumber, HashSet<LineNumber>, BuildHasherDefault<FxHasher>>,
    opposite_to_rhs: &HashMap<LineNumber, HashSet<LineNumber>, BuildHasherDefault<FxHasher>>
) -> Vec<(Side, MatchedPos)>
Expand description

Return a vec of novel MatchedPos values in an order suited for displaying.

Since novel positions don’t have a corresponding opposite position, use the last opposite matched position to decide ordering.