A function returned the element to remove from a bucket, instead of its
position in that bucket. This function was only called when a tried
bucket overflowed, which only happens after many outgoing connections
have been made.
Closes: #1065, #1156
This commit removes the dependency of serialize.h on PROTOCOL_VERSION,
and makes this parameter required instead of implicit. This is much saner,
as it makes the places where changing a version number can have an
influence obvious.
Design goals:
* Only keep a limited number of addresses around, so that addr.dat does not grow without bound.
* Keep the address tables in-memory, and occasionally write the table to addr.dat.
* Make sure no (localized) attacker can fill the entire table with his nodes/addresses.
See comments in addrman.h for more detailed information.
