Build on latest ubuntu

• Build on latest ubuntu
• Fix panic
• Update Dockerfile
• Dockerfile: make youtube-dl available under multiple names
• Move keyboard shortcuts in README

Upgrade dependencies

• Upgrade dependencies

Fix release scripts

• Fix release scripts
• Fix build

Add playback range in audio element

• Add playback range in audio element
• Upgrade dependencies
• Remove weird unicode character from README

Reduce Docker image size, comments in configuration file, style adjustments

• Reduce Docker image size
• Support comments in configuration JSON
• Adjust song page styling for #7
• Upgrade dependencies

Improve song page design, support comments in configuration file

• Update screenshots
• Note on comments in config file
• Adjust song page styling for #7
• Support comments in configuration JSON
• Delay cover image preload
• Upgrade dependencies

FTP: fix special char handling in artist & album

• FTP: fix special char handling in artist & album