Easy spacing fixes, trailing stuff

Remove useless trailing \
Remove trailing spaces
Add missing empty lines

autopep8 -ir -j2 --select=E301,E302,E502,W291,W293,W391 .

Diff quickly checked.

weboob/core/bcall.py

@@ -43,13 +43,16 @@ class CallErrors(Exception):
     def __iter__(self):
         return self.errors.__iter__()
 
+
 class IResultsCondition(object):
     def is_valid(self, obj):
         raise NotImplementedError()
 
+
 class ResultsConditionError(Exception):
     pass
 
+
 class BackendsCall(object):
     def __init__(self, backends, condition, function, *args, **kwargs):
         """