Ensure InitPIDstate() calcs correct diff
Ensure InitPIDstate() calcs correct diff

It seems the issue at 0.3.9 was that InitPIDstate() could have used
wrong average values when wallets initialized at different block
heights. But, I couldn't duplicate it.

kryptohash/kryptohash,kryptohash/kryptohash,kryptohash/kryptohash,kryptohash/kryptohash,kryptohash/kryptohash