lemma about differences of convex functions

lemmas relating ln x and x - 1

use divide instead of inverse for the derivative of ln

adding ISABELLE_GHC environment setting to mira configuration isabelle makeall all on lxbroy10

renamed Drule.instantiate to Drule.instantiate_normalize to emphasize its meaning as opposed to plain Thm.instantiate;

document depth arguments of method "auto";

clarified raw_blast, which is not really a tactic since it operates directly on subgoal 1 without bounds check (cf. c46107e6714b); uniform handling of exceptions in depth_tac and blast_tac, discontinued separate blast_depth_tac; tuned blast_tac: atomize prems only once, outside DEEPEN;

clarified special incr_type_indexes;

tuned signature: Name.invent and Name.invent_names;

modernized structure ProofContext;