Wishlist: iteration len()-type operator

```
Rather than have an application provide an iterable list of objects (like,
say, 'changes') *and* a value like 'num_changes', it'd be right handy if
the template could simply ask for the length of the list in some way.
```

Original issue reported on code.google.com by `cmpilato` on 19 Dec 2008 at 6:57
