work on jump insertion continues

Now registering CodeListener instead of PositionListener
Also instead of on the previous, in itself, which is simpler
and allows to react to insertion at end

lib/parfait/binary_code.rb

@@ -39,11 +39,7 @@ module Parfait
 
     def extend_one()
       @next = BinaryCode.new(1)
-      if Risc::Position.set?(self)
-        Risc::Position.log.debug "extending one in #{self}"
-        my_pos = Risc::Position.get(self)
-        Risc::CodeListener.init( @next , my_pos + self.padded_length)
-      end
+      Risc::Position.get(self).trigger_inserted if Risc::Position.set?(self)
     end
 
     def ensure_next