Simplified proof because of better simplifier.

Various new lemmas. Improved conversion of equations to rewrite rules: (s=t becomes (s=t)==True if s=t loops).

added transfer: theory -> thm -> thm;

oops;

The simplifier has been improved a little: equations s=t which used to be rejected because of looping are now treated as (s=t) == True. The latter translation must be done outside of Thm because it involves the object-logic specific True. Therefore the simple loop test has been moved from Thm to Logic.

fixed dependencies;

transfer thy Ord_nat;