refactors static content in containers into a list provider class
ensure we (re)select an item within the current range when updating listprovider content
adds SetVisibleCondition to CGUIStaticItem
adds <target> to directory nodes for specifying what type of content the node contains, or to which window it is most suited.
allow hidden library:// nodes to be listed using DIR_FLAG_GET_HIDDEN
adds a list provider for directory content. Specify via <content target="video">path/to/content</content>
adds initial menu structure
add new menu:// URL format for menu customisation
adds support for switching windows based on menu:// paths from media windows
[WIP:confluence] hack confluence home to use new menu system
WIP: flattening button needs cleanup