Newplaylist

New playlist and sources proposal

The current playlist is a mix between 'playlists', list of playable elements (in the M3U way) and list of elements by source. This is confusing, and does not match the "playlist" definition.

• split the current playlist in 2 components: "The Playlist" (M3U way) and "The sources"
• The playlist just becomes the interface for loading/managing/exporting URI lists (M3U), or subplaylists
• The sources list is the current playlist window without the "M3U" part
• The sources list has drag & drop & buttons to add URI to the M3U playlist

By extension:

• We drop the current open file/open DVD/capture interface. We replace it by the sources, and create new sources accordingly.
• The open file/dvd menus dissapear and is replaced by "open source/media"
• Each configuration menu is backported into the sources interface (see schema) split with Qtoolbox like widget.
• Ideally, each widget is redefined as a qtcreator xml widget.

Prior requirements

• Make sure that every playlist element is reacheable by URI.