Improve AddressManager address selection techniques

[svarogg]

The current address selection technique might take a few minutes before a good address is found. There have been multiple suggestions on how to improve the process.

We'll use this ticket to discuss possible solutions, then implement the ones we decide on.

[svarogg]

One thing we might want to do is send connectionFailedCount during address exchange.

A concern I have with this solution is that it might create a situation where some nodes will receive most incoming connections, while newer nodes will be neglected, creating hubs and thus centralizing the network.