Changes
* Add `-o`, `--output` flag to specify directory where cropped images are to be dumped.
- Error out if output folder set to current directory, i.e. `-o .`
- If directory doesn't exist yet, create it.
- If no face can be found in an image in batch, it is still copied over to `-o` folder.
- If no output folder is added, ask for confirmation ([Y]/n), and destructively crop images in-place.
* Use `-i`, `--input` flags as synonyms for `-p` or `--path`: symmetrical in meaning to "output".
- Is now standard nomenclature in documentation.
* `--input` or `--path` flag is now optional.
- Standard behaviour without input folder is to non-recursively process all images in immediate folder, i.e. `-p .` as currently implemented.
Breaks
* Removed all mentions of the hard-coded 'bkp' and 'crop' folders
* Calling autocrop without specifying an input path, i.e. `autocrop` does not look for the 'images' folder anymore.