Add support for disabling folding of directories (`--no-folding` in Stow)

[soredake]

More info on this option can be found here: https://linux.die.net/man/8/stow https://news.ycombinator.com/item?id=7927930

[ralish]

Worth considering and shouldn't be that difficult. I expect this is far easier than the hardlink support in #9.