Remove the QString client version from events.

It was a leftover from an old protocol.
Fix the event timestamp size (32 bits vs 64 bits).
Use a separate socket for reading datagrams on the client.

Qt connectToHost method binds the socket to another (random) port, so we
need to use another socket to be able to know which port to use to read.
Fix the ping packet IDs (plus some ID logging).
Log socket errors.
Log pong packets sent by the server.
Log the ID of received events.
Correctly initialize the server first packet & (received) event id.