Problem: No functionality to avoid specific IPs when generating
IPs for peers.

Solution: Add `ignore` command (only IPv4 for now).

Problem: `ignore` command was implemented only for IPv4.

Solution: implement for IPv6.

Problem: Current implementation is quite hard to understand.

Solution: Store reserved peer IPs in hashmap.

Problem: Ignored ranges and multiple IP networks introduced
difficulties in Peer ID -> IP mapping.

Solution: Allocate new peer IPs without using id and store them
in PeerInfo.

Problem: no tests for ignoring ip ranges.

Solution: add tests. Find bugs and fix them.

Problem: IP range is allowed to be ignored even if it contains
assigned IPs.

Solution: Abort ignore operation if necessary.

Problem: Sometimes it's more convenient to ignore everything
except specific IP range.

Solution: Implement `unignore` command by using already implemented
networks subtraction.

11 avoid specific ips

Solution: Add a map in Wireguard Networkinfo that contains
pre-shared keys for each pair of hosts.
Add command that generates keys on demand.