adding types to layout

so we can test assignment

lib/soml/compiler/class_field.rb

@@ -10,7 +10,7 @@ module Soml
       index = for_class.object_layout.variable_index(name)
       #raise "class field already defined:#{name} for class #{for_class.name}" if index
       #puts "Define field #{name} on class #{for_class.name}"
-      index = for_class.object_layout.add_instance_variable( name ) #TODO need typing
+      index = for_class.object_layout.add_instance_variable( name , type )
 
       # not sure how to run class code yet. later
       raise "value #{value}" if value