Remove mother class of the filters from the decorated Stream class

bob/io/stream/stream.py

@@ -244,8 +244,7 @@ def stream_filter(name):
 ################################################################################
 # Stream Filters
 
-### default filter ###
-@stream_filter("filter")
+### Filter general class ###
 class StreamFilter(Stream):
     def __init__(self, name, parent):
         super().__init__(name=name, parent=parent)