[Monocle] Refactored stuff into EmitSelected() and CenterOn().
[Monocle] Keep the list and position of current annotation.
[Monocle] AnnManager::select{Prev,Next}().
[Monocle] Prev/next annotation actions.
[Monocle] Implement IHaveShortcuts.
[Monocle] Configurable prev/next annotation shortcuts.