implement assignment normalisation

especially when the value is a send that needs normalising
fixes several broken tests

test/vool/to_mom/send/test_send_args_send.rb

@@ -0,0 +1,33 @@
+require_relative "helper"
+
+module Vool
+  class TestSendArgsSendMom < MiniTest::Test
+    include MomCompile
+    include Mom
+
+    def setup
+      Risc.machine.boot
+      @ins = compile_first_method( "a = main(1 + 2)" )
+    end
+
+    def test_array
+      check_array [MessageSetup, ArgumentTransfer, SimpleCall, SlotLoad, MessageSetup ,
+                    ArgumentTransfer, SimpleCall, SlotLoad] , @ins
+    end
+
+    def test_one_call
+      assert_equal SimpleCall, @ins.next(2).class
+      assert_equal :+, @ins.next(2).method.name
+    end
+    def test_two_call
+      assert_equal SimpleCall, @ins.next(6).class
+      assert_equal :main, @ins.next(6).method.name
+    end
+    def test_args_one_l
+      left = @ins.next(1).arguments[0].left
+      assert_equal Symbol, left.known_object.class
+      assert_equal :message, left.known_object
+      assert_equal [:next_message, :arguments, 2], left.slots
+    end
+  end
+end