added quick_and_dirty flag;

--- a/src/Pure/ROOT.ML	Mon Jun 29 21:33:35 1998 +0200
+++ b/src/Pure/ROOT.ML	Tue Jun 30 14:41:27 1998 +0200
@@ -55,6 +55,8 @@
 
 use "install_pp.ML";
 
+val quick_and_dirty = ref false;
+
 (*several object-logics declare theories named List or Option, hiding
   the eponymous basis library structures*)
 structure BasisLibrary =