Conversation trees works pretty bad with the current layout, javascript
etc. So it's best if we separate it and work on it as a side-project. The
oldschool settings are currently being deprecated (or broken out like this).
I'll wait with removing User preferences for oldschool conversation tree,
since that might be reusable data. But I guess it will go in the near future.
Numbered parameters when more than one used in a message.
L10n updates for consistency.
i18n for non-translatable exception.
Updated translator documentation.
Removed superfluous whitespace.
There were some differences between defaults for the
NoticeStream::getNoticeIds() function and some of its subclasses'
implementations. So, I got them rationalized.
Added filtering code so that notice streams check notice scope.
Added new class to implement filtering a stream, FilteringNoticeStream.
Added a subclass that does the logic for checking Notice scope.
And made all the streams use ScopingNoticeStream.
