Expand version prefix to 3/4 digits

We currently use a 10-foo, 20-foo version prefix and sort based on that. With the current approach of skipping 10 every version (so version 2 is actually 20-foo) we have 9 versions before we go into 100-foo. At that point we need to worry about sort implementations that may put "100" before "10". Might be best to update to a three or four digit version now so we don't have to think about this for a while, i.e. "010-foo" or "0010-foo".

I wouldn't mind the latter because my eye is quite accustomed to that from the git patch prefix.