napsterv

Results 2 issues of napsterv

**Pull request recommendations:** - Feature/slice pil image - Merge conflicts fixed for #22 - `slice_PIL_Image` function can be used for slicing an already opened PIL image.

Image1 ![Screenshot from 2020-02-24 19-53-01](https://user-images.githubusercontent.com/8555852/76735662-658bd780-678b-11ea-8436-5516e3d4ce6f.png) Image2 ![Screenshot from 2020-02-24 19-53-13](https://user-images.githubusercontent.com/8555852/76735664-66bd0480-678b-11ea-8aec-ecd73e50f70d.png) Image3 ![Screenshot from 2020-02-24 19-53-18](https://user-images.githubusercontent.com/8555852/76735665-66bd0480-678b-11ea-9500-09d718f2493e.png) Images attached above.