Small rewrite of Player init logic
Small rewrite of Player init logic

- only currently used Player.engine is initialized
- external JS APIs are lazy-loaded on first use
- YT player does not need to be first (closes #97)
- SoundCloud now has minimalistic splash screen

lidel/yt-looper,sk4zuzu/yt-looper,lidel/yt-looper,sk4zuzu/yt-looper,lidel/yt-looper,sk4zuzu/yt-looper