Feature/add review pr option

use `./eb --review-pr 1017 -D | less -R` to try this out.
TODO:
 - [ ] Compare with other files found in the same PR
 - [ ] add legend on top
 - [ ] add documentation / docstrings
 - [ ] figure out how to display added/removed spaces



@nudded: how can `extract_file` check which directory it just created, if files/directories are already present in the target path? I guess it could diff directory contents before/after unpack...