Changes

Summary

1. misc tuning and clarification;
2. tuned;
3. misc tuning and clarification, following Term.incr_bv / Term.incr_boundvars;
4. tuned;
5. tuned;
6. minor performance tuning: regular Same.operation;
7. clarified signature: more standard argument order;
8. clarified signature: more standard argument order;
9. tuned whitespace;
10. tuned: more standard names;
11. clarified signature;
12. tuned: prefer Same.commit;
13. tuned: more standard argument order;
14. clarified signature;
15. more operations; more caching;
16. tuned comments;