Vim 7.0 added a new feature named **Undo branches**. Basically it's a kind of ability to go back to the text after any change, even if they were undone. Vim stores undo history in a tree which you can browse and manipulate through a bunch of commands. But that was not enough straightforward and a bit hard to use. You may use `:help new-undo-branches` or `:help undo-tree` to get more detailed help.
Now this plug-in will free you from those commands and bring back the power of undo tree.
This script is written purely in Vim script with no additional dependency.