[BUGFIX][Processing] Vector tools -- add next methods for features iterator

Author: rldhont

python/plugins/processing/tools/vector.py

@@ -130,6 +130,10 @@ def filterFeature(f, ignoreInvalid):
         def __iter__(self):
             return self.iter
 
+        def __next__(self):
+            '''Iterator next method in python 3'''
+            return next(self.iter)
+
         def __len__(self):
             if self.selection:
                 return int(self.layer.selectedFeatureCount())