Changes

Summary

1. some remarks on division
2. proper section headings
3. more NEWS;
4. clarified NEWS;
5. performance tuning: replace Ord_List by Set();
6. tuned;
7. performance tuning: replace Ord_List by Table();
8. more Set() and Table() instances;
9. tuned;
10. performance tuning: replace Ord_List by Set();
11. performance tuning: make_size accounts for boxes, i.e. pointer derefs required in "count";
12. NEWS;
13. performance tuning;