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



hmm... you should at least issue a log warning message when there's more than one easyconfig, although in practice this shouldn't occur anymore (since all the easyconfigs we ship don't include multiple 'blocks', which is a legacy feature)