Minor cleanups
Make the object iterator work on objcore and get rid of ims_obj.
Move STV_Freestore() to ObjSlim()
Eliminate req->obj.

Until reimplemented we have slightly less info in panics about objects.
Retire various struct object related infrastructure.
Rewrite the esi_include delivery to use ObjIter()
Skip NULL and empty arguments when hashing. Hash all other arguments.

When multiple arguments were passed to vmod_hash_backend, only the
first argument was re-used for the number of arguments passed.

Fixes #1568
Change the main esi_deliver loop to also use ObjIter
Set the OA_VARY through the API.
Wording
Describe bereq.retries