Give ability to compare two history versions

[ravishivt]

Similar to how a Wiki works, it would be very useful to be able to compare the differences between two historical versions or to compare the differences between the current version and a historical version. The comparison tool should look at all fields that are common to both versions and show a visual diff between each pair's values.

django-reversion has an add on to give this comparison ability. It would be great if django-simple-history had the functionality as well.

https://github.com/jedie/django-reversion-compare

[treyhunner]

Great idea.

django-moderation uses a visual diffing tool (see screenshot in README) that might be helpful for this.

Pull requests welcome.

[rossmechanic]

duplicate of #396