Convert SimpleCall to new regs

Also fix bug in RegsiterValue/Slot with chain, where logic was dodgy and compiler not set

test/slot_machine/instruction/test_simple_call.rb

@@ -7,27 +7,30 @@ module SlotMachine
     def instruction
       SimpleCall.new( make_method )
     end
-    def test_len
+    def est_len
       assert_equal 7 , all.length , all_str
     end
     def test_1_load_return_label
-      assert_load risc(1) , Risc::Label , :r1
+      assert_load risc(1) , Risc::Label
       assert_label risc(1).constant , "continue_"
     end
     def test_2_load_next_message
-      assert_slot_to_reg risc(2) ,:r0 , 1 , :r2
+      assert_slot_to_reg risc(2) ,:message , 1 , :"message.next_message"
     end
     def test_3_store_return_address
-      assert_reg_to_slot risc(3) , :r1 , :r2 , 4
+      assert risc(3).register.is_object?
+      assert_equal 4,  risc(3).index
+      assert_equal :"message.next_message",  risc(3).array.symbol
     end
     def test_4_swap_messages
-      assert_slot_to_reg risc(4) ,:r0 , 1 , :r0
+      assert_slot_to_reg risc(4) ,:message , 1 , :message
     end
     def test_5_call
       assert_equal Risc::FunctionCall , risc(5).class
       assert_equal :meth , risc(5).method.name
     end
     def test_6_label
+      assert_equal Risc::Label , risc(6).class
       assert_label risc(6) , "continue_"
     end
   end