- converted from Python2 code to Python3 code

- in camlib.py, CNCJob class -> generate_from_excellon_by_tool() was
failing in the line to sort the tools due of been unable to compare
between dict's. I replaced that section.

tests/test_tclCommands/test_TclCommandExportGcode.py

@@ -1,8 +1,8 @@
 import os
 import tempfile
 
-from test_TclCommandCncjob import *
-from test_TclCommandDrillcncjob import *
+from .test_TclCommandCncjob import *
+from .test_TclCommandDrillcncjob import *
 
 
 def test_export_gcodecncjob(self):