removed obsolete HOL/Library/Coinductive_List.thy, superceded by thys/Coinductive/Coinductive_List.thy in AFP/f2f5727b77d0;

removed old CVS Ids; tuned headers;

reverted fe9b43a08187 -- "warning" is a perfectly normal way of tactics to emit spurious messages (although "arith" could be less chatty), while "priority" is a special Proof General protocol message;