Layouts: manageVisibility defaults to false. List, GroupedList: default layout manages visibility.
Examples/Themes: manageVisibility tweaks. AeonDesktopTheme: doesn't create layout objects for all lists; uses default.
LayoutExplorer: migrated to PanelScreen. simplified theme creation. fixed hardware back button on tablets.
Examples: simplified theme creation
Components Explorer: android back button fix for tablets.
ButtonGroup: support for isEnabled in button initializer (closes #332)
ScreenNavigator: extended documentation for transition property.
FocusManager: better focus changing in both directions and browser support.
AeonDesktopTheme: turns on focus manager