DFLTCC update for window optimization from Jim & Nathan

DFLTCC update for window optimization from Jim & Nathan

Stop relying on software and hardware inflate window formats being the
same and act the way we already do for deflate: provide and implement
window-related hooks.

Another possibility would be to use an in-line history buffer (by not
setting HBT_CIRCULAR), but this would require an extra memmove().

Also fix a couple corner cases in the software implementation of
inflateGetDictionary() and inflateSetDictionary().