storing the hash multiplier instead of the hash value

[Walter Bright]

Andrei Alexandrescu wrote:
> Better suggestions are always welcome. For integrals I'm unclear on what 
> we could use to make things better. (Clearly we could and should get rid 
> of the extraneous field.)

Unfortunately, it won't be much of a win. Memory allocation is done in buckets 
of size 16, 32, 64, etc. Reducing the node size for a uint[uint] from 16 to 12 
saves no memory at all.