Changes

Summary

1. clarified signature;
2. clarified compiler output: allow multithreaded execution;
3. clarified signature: more operations;
4. clarified props: more permissive;
5. more robust;
6. clarified properties: "module" and "no_build"; clarified signature;
7. clarified signature;
8. clarified signature;
9. tuned comments;
10. tuned document;