Merge pull request #24 from boneskull/master

changed History.forget() API
Merge pull request #26 from boneskull/master

fixed binding problem; v bump
Merge pull request #34 from boneskull/master

resolving several issues
Merge pull request #35 from boneskull/master

more memory leak fixes
Merge pull request #36 from boneskull/master

adding travis-ci webhooks
[Bugfix] in the _do function

- a copy of the historic value must be assigned instead of the object itself
  otherwise undoing or reverting to a historic step and starting with new edits
  from there will have the effect that the historic value on the stack from
  where we have restarted will always be changed the latest value.

- added test
Merge pull request #38 from bernhard-niedermayer/bernhard-niedermayer/patch-1

[Bugfix] in the _do function