removed pretty_theory, pprint_theory (see context.ML or thy_info.ML);
removed obsolete pretty_name_space;
accomodate identification of type Sign.sg and theory;
* May 2005: Rafal Kolanski, NICTA
Substantially improved retrieval of facts from theory/proof context.
* May 2005: Florian Haftmann, TUM
Several new antiquotation.
* February 2005: Lucas Dixon, University of Edinburgh
Substantially improved subst method.
$Id$