context-refactoring: don't use `__slots__`
I couldn't get any noticeable performance difference anyway, and ... [http://groups.google.com/group/comp.lang.python/browse_thread/thread/4d0aa0ce90ee9eab/ __slots__ are evil]...
Authored by: cboos 2007-10-26
Parent: [r6105]
Child: [r6107]
