[gbmuwkqr] 2^64 should be enough for anyone

We are quite surprisingly approaching the limits of 64-bit addressing, especially in things like disk storage.

The first to fall will be an artificial task of addressing individual bits with a signed 64-bit integer, so max 2^63-1: 2^63 bits = 1153 petabytes = 1024 pebibytes = 1 exbibyte = 1 large data center.