minor ForNode.render reversed optimization

[(removed)]

short version, nestled snuggly in django.template.defaulttags.ForNode.render is a homebrewed native reverse implementation; aside from it using range when it should be using xrange, this is fine for <py2.4; for >=py2.4 however, the builtin reversed should be used (fair bit faster among other things).

So... attached is a patch doing just that; for folks using >=2.4, it's a linear 10x boost (mass index lookups kill kittens when in combination with native py vs cpy speeds), so... worth adding.

[Malcolm Tredinnick]

Indeed! Looks good.

[Malcolm Tredinnick]

(In [5454]) Fixed #4462 -- Use builtin reversed() function when available (in "for" tag).
Thanks, Brian Harring.