libcore|RuleRectangle: Added convenience method for defining mid X/Y rules
libappfw|Data: Added method for iterating all items of a data model
libappfw: Popup menu annotation hiding; button style changes

The variable 'Config.ui.showAnnotations', which PopupMenuWidget
now expects to find in the Config, determines the visibility of the
annotation items.
UI|Client: Reorganized the console popup menu; showing/hiding annotations

The console popup menu was split into a log history menu and one for
controlling the command prompt behavior. A new icon was added for the
log.

There's a new shortcut for toggling Script mode: right-click on the
prompt [Cmd/DS] button.
Fixed: Missing header
Merge branch 'master' of https://github.com/skyjake/Doomsday-Engine