Spotify Web 1.65 - Automatic Musixmatch token fetching through a separate WebView

Adds automatic Musixmatch token fetching to Web Lyrics+. Tap the Musixmatch link in the Set your Musixmatch User Token window and sign in on the screen that opens over the player. The app reads and saves your token, closes the screen and reloads the lyrics.

Google sign-in works using the same fix as Spotify's Google login. Sign-in popups open over the screen and close automatically. Back goes one page back, and closes the screen when there is no page left.

With Debug Logging on in Settings, the Logger shows lines for this screen: the Musixmatch pages it visits, its requests and the hand-over of the token. Query strings and token values are not logged.

Lyrics+ userscript 17.67 includes the feature and updated instructions. The manual token fetching process outside the app is unchanged. Userscript 17.68 also moves the Musixmatch lookup to Musixmatch's signed web API, after Musixmatch removed its old route, and follows zensu357's pull request fix/musixmatch-signed-web-api for bettergnome-lyricsbar. Thanks to its author. The script loads from GitHub on every launch, so updating the app is enough.

Limits: the signed web API is unofficial and its key comes from Musixmatch's own website code, so Musixmatch can break it again at any time, without an app change.