PATCH: Minor method prototype doc typos in SplDoublyLinkedList

Thanks for the new SplDoublyLinkedList class - I'm looking forward to taking
it out for a spin.

Here's a patch for a few minor typos in the method docs:

http://scratchpad.coffeecode.net/proto_typos.diff

There are some problems in the current implementation, I'm waiting for Etienne to talk about it.
One particular issue is that dllist_002.phpt makes valgrind very unhappy - http://phpfi.com/290107

--
Wbr,
Antony Dovgal