#243 Serial processing of audio tracks, fix the progress counter

[Borewit]

• 244: Ensure callbacks are called in media-handler

• 243: Serial processing of audio tracks, fix the progress counter

• Replace abandoned dependency musicmetadata with music-metadata
• Add additional audio formats: M4A, MP2, MP4, FLAC, WMA, ASF, OGG, OPUS, WV, WAV

These are some improvements, but there is yet more work todo.

[jansmolders86]

Dope! Much obliged helping keeping this alive!