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



this is the code pbsmon (which could be used as another fallback)
```python
def get_row_col():
    """Get the dimensions of current terminal in row,col"""
    row, col = 24, 80

    stty = '/usr/bin/stty'
    if os.path.exists(stty):
        try:
            row, col = [int(x) for x in os.popen('%s size 2>/dev/null' % stty).read().strip().split(' ')]
        except:
            # do nothing
            pass
    row = os.environ.get('ROWS', row)
    col = os.environ.get('COLUMNS', col)


```