Changes

Summary

1. merged
2. tuned;
3. tuned signature -- eliminated clones;
4. command 'interpret' no longer exposes resulting theorems as literal facts;
5. more robust normalization of witness, e.g. relevant for proofs of transfer_existence_ivl0, transfer_flow0 in AFP/thys/Ordinary_Differential_Equations/Numerics/Transfer_Euclidean_Space_Vector.thy;
6. tuned;
7. more standard instantiate operations, where substitutions are already certified and stored with trimmed theory certificate;
8. explicit operations to instantiate frees: typ, term, thm, morphism;
9. more operations for ctyp, cterm;
10. minor tuning and clarification;
11. minor tuning and clarification;
12. tuned signature;