gpu-next for linux and windows, small changes to osx

[Xathros1]

For discussion. Open for changes

NEEDS MPV 0.35.0+

• Added and adjusted lines for gpu-next on linux and windows (new libplacebo-based renderer).
• Added some shaders to choose from, defaults to Ravu-zoom-r3-rgb, as before.
• Added Profiles: Upscaling & Processing Based on Source Video's Resolution (Croma, deband, interpolation)
• Deleted mordenx.lua, the alternative OSC, cause I can't get it to run properly, so I adjusted the default OSC. Upstream was not very helpful.
• Added fonts, for osc, stats & subs
• Updated webm.lua and KrigBilateral shader that was already there
• Added playlistmanager.lua
• ytdlautoformat.lua
• updated readme
• dunno if I've missed anything I've only tested it on Linux for now

[Tsubajashi]

Thank you, so far it looks good! if there are any issues, they can be fixed at a later date! :)