Reliable connection

[hnisula]

• Connection request and answer.
• Timeout if no response for X seconds.
• Support for reliable packets (resend if no ACK).
• Maybe some kind of heartbeat packet to keep connection alive if no other packets have been received.
• Regular packets act as keep-alive packets.

[hnisula]

To test reliability there must be a way to simulate packet loss and extra latency like #63 .