Refactor|libdeng2|Client: Actions are able to duplicate themselves
Fixed|UI|Client: Include the correct header (uidefs.h)
libdeng2|Widget: Added Deletion audience; children can be reordered
UI|Client|GuiWidget: Added a nicer way to get child widgets
UI|Client: Added a data model abstraction (context with items)

Added ui::Context, ui::Item and ui::ListContext. Context holds Items.
ListContext is a concrete list-based implementation.

See apidoc for full description.
UI|Client: Added a controller that creates widgets out of a data model

ContextWidgetOrganizer links with a context and
constructs/updates/deletes child widgets corresponding to
the context's items.
UI|Client: Added specialized ui::Items for actions and variable toggles
UI|Client|Project: Updated project file with all new sources
Refactor|UI|Client: Use ui::Context in menu-based widgets

ui::Context provides a uniform way to manage a set of items for
menus. It is now used for all menu-based widgets (regular menu, popup
menu, game selection).

Specialized menus tap into the base class's Organizer to gain access
and customize the created widgets.
Refactor|UI|Client|Console|Task Bar: Updated for ui::Context

It is now simpler to populate menus with items.