derive binary code form word

long ago hacked the binary code to use integers (thus forsaking correct
arm binaries)
Finally fix by deriving from Word which now has correct binary access
Dumped binary.name in the process, that is available from the method

test/parfait/helper.rb

@@ -29,7 +29,7 @@ HERE
       @interpreter.tick
     end while( ! @interpreter.instruction.nil?)
     assert_equal @stdout , @interpreter.stdout
-#    write_file if true
+    write_file if true
   end
 
   def write_file