[antlr-interest] TreeNodeStream implementation

[Terence Parr]

Heh, I've been building a node stream that is much faster and simpler  
than current CommonTreeNodeStream, but requires that I make an array  
of node pointers that point into the tree.  It will be much more  
suitable to interpreters etc... because it can jump around.  So it's  
faster and simpler, but costs memory for that array.

Q: Shall I make this the CommonTreeNodeStream and then make current  
one another name like UnbufferedTreeNodeStream?

Later I will even make an IndexedTreeNodeStream for really fast rule- 
based translation...where are my grad students when I need them!  Oh,  
I don't have any...that's right.

I know most people in western world are on vacation, but anybody from  
Asia or wherever wanna comment?  Should we buffer the tree node  
stream just like we do for the token streams by default?

Ter