Elapsed and ETA times roll over for long renders

[luksteph]

I'm finishing up a 50+ hour render right now, and it's kind of ambiguous how much time has elapsed and how much time is remaining. This would be fine for renders under 24 hours long, but for people on slow hardware or with large maps, it should be clarified.

Current implementation: Elapsed: 12:05:52 ETA: 02:26:32

Proposed: Elapsed: 60h05m52s ETA: 02h26m32s