Automagically save aTV settings.

Save the settings when the user leaves the settings menu. No need to
safely shut down PlexConnect for the settings to be saved.
Separate out change fanart menus.

Adding the fanart to the change poster menus causes the aTV to load
tomany images and can sometimes cause a crash :(
Rename 'Artwork' to 'Poster' / 'Fanart'
Respond to the aTV when requesting to save settings.
Keep Baa happy ;)
Fanart sesaon list fix missing image.....

if season has no art.
add ratingKey to cache filename
TVShow preplay screen: add direct play for additional episodes (button PLAY)
music/playlist: controls tweak - "select" is main

Limited to music section and playlist (audio + video):
- SELECT to start continuous replay
- PLAY to replay just single track/video
For audio this is essentially a button switch, for playlist video the
preplay screen is lost… (shall it be pushed into scribble menu?)
Make 'PIL/Pillow not installed' item unselectable
Fix xml names - Linux filenames are case sensitive
add "now playing". missing JS to hide item. :-(

there are some (more or less) native functions out there, called
atv.nowPlaying.willStartPlaying/willStopPlaying/didStopPlaying/playerSta
teChanged/currentAssetChanged/currentAsset to create a hiding script…
but I have dumped too much time here, without a result so far. :-(
fix spelling (please re-hide shared libraries, if needed/wished)
new POT - did we really change that much?
PILBackgrounds - disable for iOS prior to 6.0
Fix ByFolder post-play navigation

Reference:
https://forums.plex.tv/index.php/topic/129936-menu-navigation-problems/
Do we really need this “volatile=*” everywhere?
Unplayed/partiallyPlayedDot is not shown in Grid view!
tweaks on aTV2 installation instructions
add short note on PILBackgrounds
replace loadURL overrides by onGenerateRequest
onGenerateReq: allow non-std. URL parameters