Support 64bit address hashing in the CommonHashClass.

The class already supports hashing 64bit values, just break it out to support it in this particular case.
From the 64bit version of the hash, this hash favours values that aren't on the extreme end.
Consdering that hashing is only really used by the class itself it isn't too big of an issue.

Also this can be merged prior to PR #109, it'll correctly fall back to the 32bit route everywhere.