PATH: post processor tweaks and loop select.

rename generic_post.py: This is actually a post specific to a machine.  The generic name is confusing
fix test case. Contour has no plunge angle
scrubbing postprocessors for python 2 style prints
Keep loop select usable when task panel is open.

src/Mod/Path/PathScripts/dumper_post.py

@@ -69,6 +69,7 @@ def export(objectslist, filename,argstring):
         final = output
 
     print("done postprocessing.")
+    return final
 
 
 def parse(pathobj):