the strongest

big ones

• add support for external analysis tools to provide arbitrary tags for the index
• add example tools for detecting bpm and melodic key
  • https://github.com/9001/copyparty/tree/master/bin/mtag
• add range-search (duration/bpm/key/... between min/max values)
• hotkeys for changing songs + skipping
  • 0..9=jump, J/L=file, U/O=10sec, K/I=folder, P=parent

the rest

• add search timeouts and rate-control on both server/client-side
• add time markers in the audio player
• remember the file browser sort order
  • the initial html retains server order, so use the tree to navigate
• fix a race in the tag parser when using the multithreaded FFprobe backend
• fix minor stuff related to volume flags and tag-display options
• repacker should no longer break the bundled jinja2