Consider supporting ranges in the template loop tag

I would like to be able to do this when paginating:
```
#for(i in 1...page_count):
 <li class="active"><a href="/items/list/?page=#(i)">#(i)</a></li>
 ...
```
My current workaround is to create a page count array inside the application:
```Swift
let page_count = Array(1...items.pageCount)
```