SSViewer iterates on Iterators that it receives twice: first to get the
total number of items, then to actually render each item.
This necessitates a rewind. In order to make more use of generators,
which are not rewindable, I’d like to remove the need for a rewind.
I’ve done this by caching the content of the iterator as an array
within SSViewer_Scope.
Although this means a bit of memory usage, there are no cases in which
code will get to this point without iterating on all items, which would
use the memory anyway. It would only create onerous impacts in cases
where you are iterating on very long iterators, which would mean you’re
rendering a very large page anyway, and probably have other performance
issues.
