API changes

• Bumped API version number to 6.0.
• Added new endpoints to manage users, mount points and settings more granularly.
• Added support for authenticating via bearer tokens generated by the /auth endpoint. These token can be submitted via Bearer HTTP Authorization headers, or as a URL parameters (auth_token).
• Authentication using cookies or Basic HTTP Authorization headers is deprecated and will be removed in a future revision.
• Authentication cookies no longer expire after 24 hours. The newly added bearer tokens also have no expiration data.
• Last.fm account linking now requires a short-lived auth token obtain from the newly added `lastfm/link_token' endpoint.

Server

• ⚠️Breaking change⚠️ If you use a config file, please put the reindex_every_n_seconds and album_art_pattern in a [settings] section.
• ⚠️Breaking change⚠️ The installation process on Linux has changed a lot. See the README for updated installation instructions. A summary of the changes is available here.
• Embedded album art is now supported for mp3, flac and m4a files (thanks @Saecki).
• OPUS files can now be indexed and streamed (thanks @zaethan).
• APE files can now be indexed and streamed.
• The collection indexer has been rewritten for better performance. This also fixed an issue where on some machines, the web client would be unusable while indexing (thanks @Inicola for the code reviews).
• Thumbnail generation is now slightly faster, and works with more pixel formats (notably RGBA16).
• Polaris now uses actix-web instead or rocket. This change fixes numerous performance and stability issues.
• Sqlite is now bundled by default when building Polaris and was removed from the list of prerequisites. This can be controlled with the bundle-sqlite feature flag when compiling Polaris.
• The default album art pattern now includes the jpeg extension in addition to jpg.
• Album art patterns are now case insensitive.

Web client

• ⚠️Breaking change⚠️ Your current playlist will appear broken after this update. Please clear the current playlist using the trash can icon. Saved playlists are not affected.
• Added a logout button.
• Reworked interface for managing user accounts.
• Added a shuffle button to randomly re-order the content of the current playlist.
• The total duration of the current playlist is now displayed.
• Audio output can now be toggled on/off by clicking the volume icon.
• Individual discs from multi-disc albums can now be dragged into the playlist.
• When browsing to album, songs are now displayed and queued in filepath order.
• Fixed a bug where albums could not be dragged from the random or recent views.
• Fixed a bug where directories with a # sign in their name could not be browsed to.