Add recursive parameter to Playlist.Item directories

Default to false to keep consistency with Frodo
[GUIInfoManager] Cache the audio/video info for video player labels.
The cache period is one frame (move).
[GUIInfoManager] Cache the audio info for music player labels.
The cache period is one frame (move).
Merge pull request #2535 from ace20022/info_cache

[GUIInfoManager] Add a cache for audio and video info labels
Merge pull request #2559 from Tolriq/recursive_playlistitem

json-rpc: add recursive parameter to Playlist.Item directories