fix mod4 name

really did div4

lib/risc/boot.rb

@@ -181,7 +181,7 @@ module Risc
       end
 
       obj = space.get_class_by_name(:Integer)
-      [ :putint, :mod4, :div10, :+ , :- , :*].each do |f|   #mod4 is just a forward declaration
+      [ :putint, :div4, :div10, :+ , :- , :*].each do |f|   #div4 is just a forward declaration
         obj.instance_type.add_method Builtin::Integer.send(f , nil)
       end
     end

lib/risc/builtin/integer.rb

@@ -5,9 +5,9 @@ module Risc
       module ClassMethods
         include CompileHelper
 
-        def mod4(context)
-          source = "mod4"
-          compiler = compiler_for(:Integer,:mod4 ,{})
+        def div4(context)
+          source = "div4"
+          compiler = compiler_for(:Integer,:div4 ,{})
           builder = compiler.builder(true, compiler.method)
           me = builder.add_known( :receiver )
           builder.reduce_int( source , me )