Playlist grouping support

Playlist can now display grouping headers, the aggregation value can be scripted. By default we use artist - year - album.

Bugs

• Fixes many issues with Microsoft Store release (included in 2.1.2 but there was no github release)
• Adds "refresh devices" command to each output device settings page.
• Fixes some crashes when meta data extraction is disabled.
• Creating playlists is now faster due to sequencing (sorting) items are they're inserted instead of after.
• Improved indexing for the SQLite back-end should make everything faster.
• Asynchronous loading and synchronization for library and playlist views makes UI more responsive.
• Adds meta data caching.
• Library tile images and cursor adorers now respect current filter settings.
• Image caching performance was improved.
• Fix crashes when using UNC paths.
• Adds option to prefer embedded or filesystem images.
• Fix unresponsive UI due to missing hash code implementations.
• Prevent windows from being opened off screen when display settings are changed.