Prune trailing whitespaces from code and documentation

They are redundant in all pruned cases and sometimes even create some
problems, e.g., when one tries to jump through paragraphs in vi.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>

offlineimap/mbnames.py

@@ -70,5 +70,3 @@ def genmbnames():
         file.close()
     finally:
         mblock.release()
-    
-