Fix issue when calling external plugins as playmedia items / mistake on your last commit

Hey al101,

This pull request fixes an issue on my last change (fix favourites) for playmedia items which use external plugins. Basically, unquote the string for all functions doesn't work when calling plugin://video.veetle/p2p-streams. So now it only unquotes the item string for the functions of the contextmenu (add favourites,remove favourites,edit favourites), all the others remain as they were before (working).

Also added again my changes for p2p-streams to __streams.cfg. It seems that by mistake you removed those changes on your last commit. Please merge these changes and make sure you always update your local files after accepting a pull request so you don't revert changes to commits made in the meanwhile.

All the best

enen