Hook up layer tree structure with frontend (#372)

* Hook up layer tree structure with frontend (decoding and Vue are WIP)

* Fix off by one error

* Avoid leaking memory

* Parse layer structure into list of layers

* Fix thumbnail updates

* Correctly popagate deletions

* Fix selection state in layer tree

* Respect expansion during root serialization

* Allow expanding of subfolders

* Fix arrow direction

Co-authored-by: Dennis Kobert <dennis@kobert.dev>

frontend/vue.config.js

@@ -186,7 +186,6 @@ function htmlDecode(input) {
 		}
 		// eslint-disable-next-line no-cond-assign
 		if ((match = entityCode.match(/^#(\d+)$/))) {
-			// eslint-disable-next-line no-bitwise
 			return String.fromCharCode(~~match[1]);
 		}
 		return entity;