Offline B)

This release adds:

• Caching of library data
• Caching of low resolution cover art
• A refresh button that updates the above as per issue #20
• A logout button to clear the cache without updating it
• More sensible choice of cover art resolutions (the closest to 300x300 is chosen as per 7d78658)
• A change of the theme switch touch target so it's a bit larger (676e3ca)
  ...and a few dependency updates I guess.

My First PWA!!!

This release adds:

• PWA support,
• A search feature that scrubs through albums' titles and their artists,
• A notice displayed when you have no saved albums, or none of your albums match your filters;
• Various styling changes (the most noticeable being swapping out greens for pink),
• A rework of the login page,
• Google Analytics.

That took less time than I expected...

...I'm sure there's plenty of bugs to fix, linting to do and unrealised features to implement!