Merge branch 'master' into Develop

# Conflicts:
#	cps/editbooks.py

cps/helper.py

@@ -291,6 +291,7 @@ def delete_book_file(book, calibrepath, book_format=None):
             for file in os.listdir(path):
                 if file.upper().endswith("."+book_format):
                     os.remove(os.path.join(path, file))
+            return True, None
         else:
             if os.path.isdir(path):
                 if len(next(os.walk(path))[1]):