Summary
- merged
- lift BNF witnesses for quotients (unless better ones are specified by the user)
- more robust (amending add9a9f6a290): proper syntax error instead of exception for grammar with unreachable nonterminals, e.g. nonterminal f1 syntax "_F" :: "f1 ⇒ 'b" ("F _" 10);
- merged
- tuned var names (avoid h)
- more position information for oracles (e.g. "skip_proof" for 'sorry'), requires Proofterm.proofs := 1;
- a few new lemmas