For all manually-created images PNG have been kept.
- rename all icon attrs to have a `ic_` prefix
- always use `_24dp` icons, because there is no real difference, since they are vector drawables
- always use the original name found on material.io for icon drawables, as to not create confusion and possibly duplicates. Icon names can still be different from real drawable names, though I have made some of them compliant to this or maybe more meaningul.
- remove duplicate `getIconByAttr()` in ThemeHelper (use `resolveResourceIdFromAttr()`
- use standard icons for `expand_more` and `expand_less` instead of triangles
- use `play_button_outline` instead of custom PNG as play button in VideoDetailFragment (questionable, as there is no shadow anymore)
-Added seek time display to player binding activity.
-Added button effect for all image buttons on player binding activity.
-Added click to scroll to current selected on metadata layout for player binding activity.
-Refactored player utilities and preference getters into PlayerHelper.
-Refactored player caching into CacheFactory.
-Refactored player audio related methods into AudioReactor.
-Refactored player locks into LockManager.
-Refactored player loading and buffering mechanics into LoadController.
-Fixed outdated names for background player.
