Merge pull request #5941

1d21ba2 Scale up addrman (Pieter Wuille)
c6a63ce Always use a 50% chance to choose between tried and new entries (Pieter Wuille)
f68ba3f Do not bias outgoing connections towards fresh addresses (Pieter Wuille)
a8ff7c6 Simplify hashing code (Pieter Wuille)
e6b343d Make addrman's bucket placement deterministic. (Pieter Wuille)
b23add5 Switch addrman key from vector to uint256 (Pieter Wuille)