macosx: Refactor main library window split view
This is a fairly big MR that refactors the way we instantiate and manage the views within the main library window. Rather than have a huge library window class that contains all of the relevant internal views, this MR splits off the internal navigation sidebar, library target view, and playlist sidebar views into their own XIBs with their own view controllers (as the Apple documentation insists we should do this). This:
- Makes the code more manageable, maintainable, and encapsulated
- Fixes issues with library window initialisation (particularly when opening the app with collapsed sidebars, which would previously cause the views to never be instantiated, even after opening the sidebar)
- Makes it easier to manage the behaviour of the split view's items through the VLCLibraryWindowSplitViewController
Signed-off-by: Claudio Cambra developer@claudiocambra.com