Translate viewport when undo/redo change lies outside visible area

[xsot]

If undoing/redoing results in a change made to the circuit that lies outside the visible area, the viewport should be translated such that it can be seen. This behavior is implemented in various text editors, where the cursor is always kept within view and undoing/redoing positions the cursor to where the change was made.

[btzy]

This could be done together with a modification to the way history states are stored - currently history states simply store a snapshot of the whole state at that point in time, but we might want to change it so that it stores only the area that was changed.