Lua dev mode functional

Lua support feature-complete

Full implementation of debug mode still pending

Remove ResponseCtx

Use http::Response for constructing replies

Add SPDX info to all files

Theming refactor

Theming has been broken off into a seperate space, so that it'll be easier to add lua support later.

Unify import style

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.

Clippy

Cleanup

Custom font support complete

Add custom font support.

Create plain theme, do some escaping, fix some busted envvars, document themes.

lots of stuff. theming basically done, added some logging, frontend basically done.

config done

API deserialization structs