clarified setup_repository: more uniform pull vs. clone, without update;

proper setup of fresh repository;

clarified prover-specific rules

dropped potentially explosive rule for groebner simpset, with no observable effect on examples

simplified fact references

avoid effectively subsumed rules; simplified fact reference

eliminated irregular aliasses

avoid references to lemmas designed for prover tools

clarified theorem names

eliminated irregular aliasses

more standardized theorem names for facts involving the div and mod identity

transfer rules for divides relation on integer and natural

more standardized names

added lemma

de-orphanized declaration

tuned;