load morphism.ML later;

--- a/src/Pure/ROOT.ML	Sat Feb 03 23:42:55 2007 +0100
+++ b/src/Pure/ROOT.ML	Sun Feb 04 22:02:13 2007 +0100
@@ -47,11 +47,11 @@
 use "theory.ML";
 use "proofterm.ML";
 use "thm.ML";
-use "morphism.ML";
 use "fact_index.ML";
 use "pure_thy.ML";
 use "display.ML";
 use "drule.ML";
+use "morphism.ML";
 use "variable.ML";
 use "tctical.ML";
 use "search.ML";