- StoreEntry didn't need to have the method_t member, so its been

- StoreEntry didn't need to have the method_t member, so its been
  moved to MemObject->method.
- storeEntryListAdd and storeEntryListDelete are quite general.  They
  have been moved to tools.c and named dlinkAdd() and dlinkDelete().
- we want to be able to cache ALL methods, so store_key_url.c now
  always puts the request method into the cache key.
- made StoreEntry->refcount and StoreEntry->flag 16-bit shorts.