Add a patch mode for `git add --patch`
Add a patch mode for `git add --patch`

In this new patch mode, every time a line is consumed, we print out an
empty line in its place. This keeps the same number of lines in the
output, and appeases git.

scottchiefbaker/diff-so-fancy,so-fancy/diff-so-fancy,so-fancy/diff-so-fancy,scottchiefbaker/diff-so-fancy