v0.5.4 - minimize to tray, refactored custom css

• Added Version tag to toolbar
• Added Minimize to tray instead of quitting feature
• Added Generic settings text
• Fixed CSS (initial-)Load, Unload & Watch feature

For custom theme enable it in settings.

Full Changelog: https://github.com/Venipa/ytmdesktop2/compare/v0.5.3...v0.5.4