PEP 308 implementation, including minor refdocs and some testcases. It
breaks the parser module, because it adds the if/else construct as well as
two new grammar rules for backward compatibility. If no one else fixes
parsermodule, I guess I'll go ahead and fix it later this week.

The TeX code was checked with texcheck.py, but not rendered. There is
actually a slight incompatibility:

>>> (x for x in lambda:0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: iteration over non-sequence

changes into

>>> (x for x in lambda: 0)
  File "<stdin>", line 1
    (x for x in lambda: 0)
                     ^
SyntaxError: invalid syntax

Since there's no way the former version can be useful, it's probably a
bugfix ;)
diff --git a/Python/symtable.c b/Python/symtable.c
index fd95bd5..b66abc9 100644
--- a/Python/symtable.c
+++ b/Python/symtable.c
@@ -1084,6 +1084,11 @@
 			return 0;
 		break;
 	}
+	case IfExp_kind:
+		VISIT(st, expr, e->v.IfExp.test);
+		VISIT(st, expr, e->v.IfExp.body);
+		VISIT(st, expr, e->v.IfExp.orelse);
+		break;
         case Dict_kind:
 		VISIT_SEQ(st, expr, e->v.Dict.keys);
 		VISIT_SEQ(st, expr, e->v.Dict.values);