Moved to cache texture to limit duplicated methods (video and music).
Update backdrop instantly, should not cause any issues this time since
it only triggers if the url is different than the new one.
- setting in addon settings to turn on the cache feature (now for testing, maybe hidden later)
- for all new items the poster and the fanart image will be cached automatically (when setting is on)
- added a option to the plugin root options to perform full cache fill which will pull every single image to the cache.
