State refactor

[g-a-v-i-n]

• [x] gentle loading states to avoid flashing old router state during promise
• [x] link to source on songs
• [x] highlight current track in list
• [x] play/pause etc issues in Issues

[broskoski]

LGTM, wanna merge and we can continue from here?

[g-a-v-i-n]

Yeah I think that sounds good. It isn't throughly tested by any means but I'm also not aware of any outstanding bugs.