Content history view (content/history)

*Title: History

*Incentive:
Confusing at times with two version lists one in /content/versions, and one in /content/diff. With the history view, these two separate views are joined together, to more easily get an overview versions and changes.

*Documentation:
The old versions and diff views have been merged into a new view called /content/history. The new view is accessible both via the javascript popup menu in the treemenu, and the class icon. It is also accessible via traditional means using the "Manage versions"-button in the edit-view. The two old views have now been marked as deprecated.