v0.8.0 - Help modal, Styling

• Added Help/About modal, F1 / ?
• Optimize for network usage (-movflags faststart) by default for mp4/mov outputs
• Styling improvements. Internal preparation for theming support
• Improved detecting static images
• Improved filename validations
• [Linux] Fixed clipboard copy warning

Full Changelog: v0.7.2...v0.8.0