The main goal of this plugin is to avoid the E828 error one can get in vim
when trying to save a file with a very long file path and undofile enabled.
As vim saves undo files in undodir with a name equal to the original
filepath, with all / replaced with %, one can hit the OS maximum length for
files. If this happens, vim won't be able to save the undo file and will throw
the E828 error.
Well, instead of saving undo files as %original%path%of%the%file, it will
create the original/path/of/the/ folder structure inside of undodir, and
save the undo file in it.
This way, we avoid the length limit on filenames, and as an added bonus it makes pruning the undo folder much more easier.
Just use pathogen.
You still need to enable set undofile for the plugin to kick in.