Patch #2477: Added from __future__ import unicode_literals

The new PyParser_*Ex() functions are based on Neal's suggestion and initial patch. The new __future__ feature makes all '' and r'' unicode strings. b'' and br'' stay (byte) strings.
diff --git a/Include/pythonrun.h b/Include/pythonrun.h
index a4dd914..7dfff28 100644
--- a/Include/pythonrun.h
+++ b/Include/pythonrun.h
@@ -8,7 +8,8 @@
 #endif
 
 #define PyCF_MASK (CO_FUTURE_DIVISION | CO_FUTURE_ABSOLUTE_IMPORT | \
-                   CO_FUTURE_WITH_STATEMENT|CO_FUTURE_PRINT_FUNCTION)
+                   CO_FUTURE_WITH_STATEMENT | CO_FUTURE_PRINT_FUNCTION | \
+                   CO_FUTURE_UNICODE_LITERALS)
 #define PyCF_MASK_OBSOLETE (CO_NESTED)
 #define PyCF_SOURCE_IS_UTF8  0x0100
 #define PyCF_DONT_IMPLY_DEDENT 0x0200