several larger changes came together, bit of cleaning too

- all code must be in functions (which must be in classes).
— changes a fair few tests
— also changes api, as method is not recursive, not passed around
- all state in instance vars in compiler (no accessors)
- class is another such variable, surely more coming
all green again

test/compiler/test_field_access.rb

@@ -7,10 +7,12 @@ module Virtual
 
     def test_foo3
       @string_input = <<HERE
-field int a
-int foo(int x)
-  int b = self.a
-  return b +x
+class Object
+  field int a
+  int foo(int x)
+    int b = self.a
+    return b +x
+  end
 end
 HERE
       @output =  [ [Virtual::MethodEnter] , [Virtual::MethodReturn] ]