Typescript support

[Shujee]

It would be great if typescript definitions could be included in the package. I'm using it in a Vue project and Tyepscript compiler keeps complaining about non-existing function undoRedo.

[ugurdogrusoz]

@Shujee we do not have the resources to do this at the moment. If you like, feel free to make a PR on the unstable branch, so we can integrate it into our next release.