Called when a redo is run

Called when an undo is run

Backwards stack

Forwards stack, gets cleared when a new undo is added

Clear the history and take an initial snapshot. You should call this right after a load, or a new project.

Insert a new undo entry

Instigate a redo, returns true if we found a successful undo

Should be called after you make a change to your project. The snapshot system is good for self contained projects that can be serialized and deserialized quickly.

Instigate an undo. Return true if we found a successful undo