[antlr-interest] new attribute ref syntax

[Terence Parr]

here is the comment on the ActionTranslator related to translated $y,  
$x.y, $x::y notation:

/** This class embodies the translation of actions written in the target
*  language but containing special references that must be translated
*  for reasons of terseness and isolation from underlying  
implementation.
*
*  There are three forms of interest:
*
* 	$y		return value, parameter, rule or token label, predefined
* 			rule property, or token or rule reference within the enclosing
* 			rule's outermost alt. y must be a "local" reference; i.e., it
* 			must be referring to something defined within the enclosing rule.
*
* 			r[int i] returns [int j]
* 				:	{$i, $j, $start, $stop, $template, $tree}
* 					(ids+=ID)+ {$ids.size()} // .size is not used by antlr here
* 				;
*
* 	$x.y	if x is enclosing rule, y is a return value, parameter, or
* 			predefined property.  If x is a token label, y is predefined
* 			property of a token.  If x is a rule label, y is a return value
* 			of the invoked rule or a predefined rule property such as "stop".
* 			If x is a token referenced in that alt, it behaves like a token
* 			label.  If x is a rule reference in that alt, it behaves like
* 			a rule label.
*
* 			r[int i] returns [int j]
* 				:	{$r.i, $r.j, $r.start, $r.stop, $r.template, $r.tree}
* 					ID {$ID.text} s {$s.start; $s.k}
* 				;
* 			s returns [int k] : ... ;
*
* 	$x::y	the only way to access the attributes within a dynamic scope
* 			regardless of whether or not you are in the defining rule.
*
* 			scope Symbols { List names; }
* 			r
* 			scope {int i;}
* 			scope Symbols;
* 				:	{$r::i=3;} s {$Symbols::names;}
* 				;
* 			s	:	{$r::i; $Symbols::names;}
* 				;
*
*  This is the new syntax as of 11/23/2005 and should simplify things  
a bit
*  as all dynamic scope stuff is accessed with a different operator.   
Actually
*  all it does is make the set of scopes to search for $y a bit  
smaller.  Oh,
*  and I should be able to be more specific with error messages.
*/

Ter