Fix some issues related to python scripts:

- make PadArray.py compatible python2/3
- fix a wxWidgets warning in pcbnew_scripting_helpers.cpp shown in some cases

pcbnew/python/plugins/PadArray.py

@@ -212,7 +212,11 @@ class PadGridArray(PadArray):
         @param py: pitch in y-direction
         @param centre: array centre point
         """
-        super(PadGridArray, self).__init__(pad)
+
+        try:
+            super().__init__(pad)
+        except TypeError:
+            super(PadGridArray, self).__init__(pad)
 
         self.nx = int(nx)
         self.ny = int(ny)