Expands or shrinks allocated block to an allocated size of goodAllocSize(s). Expansion occurs in place under the conditions required
by expand. Shrinking occurs in place if goodAllocSize(b.length)
== goodAllocSize(s).
structQuantizer(ParentAllocator, alias roundingFunction)
Expands or shrinks allocated block to an allocated size of goodAllocSize(s). Expansion occurs in place under the conditions required by expand. Shrinking occurs in place if goodAllocSize(b.length) == goodAllocSize(s).