Added undo/redo support for blocks
Updated the History Table so that any 3 columns can be used as a primary key. Previously the history table used nid and vid which only works for nodes and revisions.
TODO:
This module will be refactored to use hooks, and all current find / replace functions will be moved to seperate modules.
The find / replace API will be simplified to make it easy for additional support to be added.
Currently it is pretty easy to add support for additional items, so I am not sure how soon I will get to this.