New pattern matching doc

[Brian Goetz]

> It's because i think we don't need to single out deconstructor from 
> the rest of the other methods that can be called by a pattern.

I get why you think that, but I think that would be a serious mistake.  
Constructors have a number of subtle differences from ordinary static 
methods -- and it turns out it makes total sense for deconstruction 
patterns to have those exact same differences compared to static "method 
patterns."

In any case, I think you're (still) jumping ahead in the story (or 
letting your own thoughts of how you want the story to end drag you off 
course.)   Can we stay focused on the topic of this document, which is 
the role of patterns in the object model?  I know you really want to get 
on to the "what does the declaration of a method pattern look like" 
part, but that's still a future conversation, and the syntax (ou 
pres-de-syntax) issues are getting in the way of discussing the far more 
important underlying concepts.