Update Grammar.g

Fixed
1. funcall is never invoked
2. Setxy command takes two arguments
3. remove the following 
postfix_expression returns [LOGONode node]
		: n=postfix_expression '(' expression_list ')'  {$node = new LOGOFunctionNode($n.node, "execute", $expression_list.node); LOGOPP.io.debug("funcall test");}
		| primary_expression {$node = $primary_expression.node; LOGOPP.io.debug("postfix->primary " + $node.id);}
		;

expression_list returns [LOGONode node]
        : n=expression_list ',' expression {$n.node.children.add($expression.node); $node = $n.node; LOGOPP.io.debug("expression_list");}
		| expression {$node = new LOGOExprListNode($expression.node); LOGOPP.io.debug("expression_list tail");}
		| {$node = null;}
        ;