v0.21.0

• Added separate settings page
• Allow cleaning up temporary files (clips and generated compilations)
• Added a slider for controlling the variation in clip lengths
• Added a slider for total compilation duration (if no music was selected)
• Allow controlling the minimum clip length
• Marker and video preview images are now WebP instead of PNG, saving a lot of disk space (there's also a button on the settings page that converts all existing images to WebP)
• Store configuration inside the application database, not in a separate JSON file (was a remnant from the early stages of the app, where it didn't have the database yet)
• Better error during the compilation generation