Changes

Summary

1. tuned;
2. clarified;
3. incremental document changes;
4. proper treatment of line that becomes empty;
5. tuned;
6. clarified Document.offset: including final position; support Document.change according to VSCode;
7. suppress vacuous edits;
8. clarified native Text.Offset versus Text.Length index Int;
9. tuned;
10. tuned;
11. tuned messages;