write a `map_plus` function

- [ ] immediate evaluation, returns a list,
- [ ] shows a progress bar by default, can be suppressed,
- start with a basic `tqdm`,
- deal with prints breaking the progress bar,
- with parallel execution, the bar should advance when a job is done, not when it starts,
- [ ] option to capture errors (a-la purrr::safely) instead of breaking the execution. By default, it should throw an error at the end so that you don't miss the errors,
- [ ] parallelize by default, using all but one core,
- [ ] switch all "pipeline" functions applied to a whole corpus to use `map_plus`,
- [ ] find a name that is better than `map_plus` (you can spend 5 minutes on this).