Time-magics

Added missing dependency

The following changes where made:

* Replaced the iPython backend to reduce overhead

Bugfixes.

The following changes where made:
* Changed `timeit()` parameter `number` to `n`.
* Changed `timeit()` parameter `repeat` to `r`.

The following changes where made:

- Changed package name from `timeit-magic` to `time-magics`
- Added `time()` and `time_()`
- Changed decorator function name `time_it` to `timeit_`
- Changed `timeit` and `timeit_` to use the same backend as the `%timeit` magic command
- `timeit` and `timeit_` now returns a `TimeitResult` object
- Removed `**kwargs` from `timeit`
- Added `ns`, `precision` and `quiet` arguments
- The first line in `timeit` multi-line statements are now used as setup as to be consistent with `%%timeit`

Bugfixes.