NetDriver time becomes unusable after long running sessions

This issue has been around for a long time (potentially UE3).

UNetDriver::Time is a float, which is updated by accumulating Delta Time during ticks. This means the longer a game runs, and the higher the server tick rate is, the more likely it is that floating point error can cause the time to never properly update.

This may cause a number of issues, but the most apparent seems to be that Handshaking fails so new clients can no longer connect.

1. Create a dedicated server.
2. Use the `slomo` command to speed up playback.
3. Wait sufficiently long, and then attempt to connect to the server with a client.

Expected:

The client connects with no issue.

Actual:

The client connection fails, appearing as though the challenge fails.

This is only one instance of the issue, but there are potentially numerous other side effects.
**Note: As of 3825875, the above repro was worked around. The underlying issue still persists.