allow parenthesizing boolean expressions as well as normal expressions

git-svn-id: svn://anubis/fart/trunk@370 7f9b0f55-74a9-4bce-be96-3c2cd072584d

parser/parser.yy

@@ -408,6 +408,9 @@ bool_expression: expression LESS expression {
                | NOT bool_expression {
                     $$ = new BoolExpressionNode('!', $2, NULL);
                }
+               | LPAREN bool_expression RPAREN {
+                    $$ = $2;
+               }
                ;
 
 assignment: VARREF ASSIGN expression {