v.1.3 Online sources and experimental API

This release allows using online media sources and introduces an experimental API.

Improvements

• Editor allows using of online media sources, in the currently supported formats
• Better keyboard support, especially in the edit view
• Experimental API and documentation
• fading indication during playback
• removed outfront dependency (in favor of browserstack usage)
• the current playback/loop mode is stored over app restarts, for each track
• minor fix when replacing a media source
• removed external workbox dependency for better privacy

Full Changelog: v1.2.2...v1.3.0