Refactored use of iteritems into function to deal with python 2.7 and 3 compatibility.

src/Mod/Path/PathScripts/post/opensbp_pre.py

@@ -48,6 +48,7 @@ Many other OpenSBP commands not handled
 '''
 from __future__ import print_function
 import FreeCAD
+import PathScripts.PathUtil as PathUtil
 import os, Path
 
 AXIS = 'X','Y','Z','A','B'  #OpenSBP always puts multiaxis move parameters in this order
@@ -145,7 +146,7 @@ def parse(inputstring):
 
             last[words[0][1]] = words[1]
             output += s
-            for key, val in last.iteritems():
+            for key, val in PathUtil.keyValueIter(last):
                 if val is not None:
                     output += key + str(val) + " F" + speed + "\n"