Change
- remove `IterTimer` (2)
- change `SimpleTimer` to `Stopwatch`, though `SimpleTimer` can still be used for backward-compatibility (9)
- change some variables `Stopwatch` (`start_time`, `end_time` and `elapsed_time`) to have `_` prefix (10)
New
- add public `start()`, `pause()`, `split()`, `reset()`, `get_elapsed_time()`, `get_cumulative_elapsed_time()` and `log_elapsed_time()` methods to `Stopwatch` (3, 4, 12)
- add `verbose` parameter to `Stopwatch.__init__()` (8)