* Add PgBindIter for encoding and use it as the implementation encoding &[T]
* Implement suggestions from review
* Add docs to PgBindIter and test to ensure it works for owned and borrowed types
* Use extension trait for iterators to allow code to flow better. Make struct private. Don't reference unneeded generic T. Make doc tests compile.
* Fix doc function
* Fix doc test to actually compile
* Use Cell<Option<I>> instead of Clone bound