dojo.event.topic: add method to delete a topic

[bill]

Add a method to delete a topic (ie, to disconnect everything subscribed to that topic).

This idea came out of a discussion about how to handle destruction of a Tree object, although it turns out not to be necessary to solve that problem.

But, it still seems like a useful feature, assuming you agree that a widget called "TreeWidget123" can conceptually "own" a topic called "TreeWidget123_clicked". (When TreeWidget123 is destroyed, the topic should disappear too, even if later on someone creates a new widget that's also called TreeWidget123.)

[alex]

fixed in SVN r3872. The new method is used like this:

dojo.event.topic.destroy("/foo/bar/baz");

[(none)]

Milestone 0.3release deleted