Merge pull request #98 from elig0n/patch-1

Removed duplicate command in commands for redefinition

autochdir will sometimes change the bufname('%') results and making i…

…t harder to tell if the buffer is belong to undotree. Switching to a buf variable would be much reliable.

Merge pull request #45 from blueyed/use-nowait-mappings

Use `<nowait>` with mappings

Only popup error message when user want's to open the undotree window

Fixed some small issue.

Stable release.

Real updated highlight for changed text.

Added saved status, relative timestamp and ability of clear undo hist…

…ory.

Add diff panel. Performance improvement.

Stable version.