Provide a lot more information when the time limit has been exceeded

```
--time-limit=30s is good for most people, but when it is exceeded there's not a
lot of information about why and what to do about it. We should definitely
improve that.
```

Original issue reported on code.google.com by `gak@google.com` on 13 Feb 2013 at 8:01

Start by locating the handling of the --time-limit option and the code that reports when the limit is exceeded. Determine what information is currently available about the timeout, then define and implement clearer diagnostics explaining why it occurred and what users can do next.

Written by the indexing model from the issue text.