Added setNeedsOffsetAdjustment to IIViewDeckView.
If loading a view into a navigation controller stack, mark it that it needs adjustment.
Handle changes in the center controller the same was as in the side controller (with transition blocks).

Formalized transition block finalizer code a bit more.
Hacking addSubView so that it handles the needs offset adjustment if it was set in loadView.

Fixes: #295