[antlr-interest] changed 'x' to "x" for v3

[Terence Parr]

Next time you grab a release of ANTLR v3, you'll note that all char  
literals must be string literals.  All unit tests and examples have  
changed.  So, you'll now do

INT : "0".."9"+ ;

instead of

INT : '0'..'9'+ ;

I thought a lot about this and I just can't justify wasting single  
quotes on char literals; it's actually easier to say that all  
literals matched are in double quotes.   Made a number of routines  
easier in ANTLR.

The only negative so far is that all the unit tests have grammars  
that are String literals in the Java program and so the grammars have  
to have the double quote escaped.  This is hideous, but I'm not sure  
we have a choice.  Here's a taste:

	public void testParserCharLiteralWithEscape() throws Exception {
		Grammar g = new Grammar(
				"grammar t;\n"+
				"a : \"\\n\";\n");
		Set literals = g.getStringLiterals();
		// must store literals how they appear in the antlr grammar
		assertEqual(literals.toArray()[0], "\"\\n\"");
	}

Ter