Format times like hh:mm:ss

I like it much better this way examples:
- `3s` (3 seconds)
- `01:21` ( 1 min + 21 secs)
- `01:20:12` ( 1 hr + 20 mins + 12 secs)
- `1::01:20:12` (1 day + 1 hr + 20mins + 12secs)
- `∞` - Infinite/indeterminate

Well, even if you don't take this, fix the "1.9 hrs" stuff at least. Nobody likes to parse and calculate what that means ;)