~aleteoryx/lfm_embed

ref: 83ba4fe37a1184b998be09b9cbe53a22c7ba9e3b lfm_embed/src d---------
Move caching to src/cache/; Finalize API parsing fixes

Font and user cache code has been moved to special files, independant from src/config.rs

API parsing changes have been properly tested, and last.fm API JSON is now trace-logged for debugging convenience.
Reliable user info; Font refactor

Hit a few more endpoints to fix missing images, fallback to default album art just in case.

Refactor the font cache into its own file.
Custom font support complete
Add custom font support.
Remove redundant HTML escaping helpers.
fix typo in plain theme breaking light mode.
Create plain theme, do some escaping, fix some busted envvars, document themes.
lots of stuff. theming basically done, added some logging, frontend basically done.
pull down user info
fix packages, implement caching
API deserialization structs