change to_risc and builtin code according to last commit

Wherever space was loaded to get to the next_message
we now load the Message factory.
Otherwise much the same, only the attribute is next_object, not next_message
The binary is growing with 1k objects per factory, so i had to fix (hack) arm to handle bigger constants
close #14

test/risc/test_linker.rb

@@ -25,7 +25,7 @@ module Risc
       assert_equal 0 ,  Position.get(@linker.cpu_init).at
     end
     def test_cpu_at
-      assert_equal "0xd1fc" ,  Position.get(@linker.cpu_init.first).to_s
+      assert_equal "0x2b91c" ,  Position.get(@linker.cpu_init.first).to_s
     end
     def test_cpu_label
       assert_equal Position ,  Position.get(@linker.cpu_init.first).class