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 add to playlist option for videos available as base list items.
-Moved video count to second row on local playlist header.
-Removed bottom line on playlist control UI.
-Removed stream id from playlist stream join table since only foreign constraint is needed.
-Added bar to playlist control UI.
-Modified local playlist fragment to no longer save when out of focus.
