fix code listener logic bug

next's position was only updated initially
previous logic relied on pushing everything long rightly
but it wasn't right, and no harm in setting position twice,
as events only fire if there is real change

test/risc/position/helper.rb

@@ -21,9 +21,8 @@ module Risc
   end
   class DummyPlatform
     def self.boot
-      machine = Risc.machine.boot
-      machine.set_platform( self.new )
-      machine
+      Parfait.boot!
+      Risc.boot!
     end
     def translator
       DummyTranslator.new

test/risc/position/test_instruction_listener1.rb

@@ -5,7 +5,7 @@ module Risc
     def setup
       DummyPlatform.boot
       @binary = Parfait::BinaryCode.new(1)
-      @bin_pos = CodeListener.init(@binary).set(0)
+      @bin_pos = CodeListener.init(@binary, :interpreter).set(0)
       @instruction = DummyInstruction.new
       13.times {@instruction.last.insert(DummyInstruction.new) }
       @position = InstructionListener.init(@instruction , @binary)