Bugfix release

• More work towards Qt 6 support.
• Some performance optimizations when reading files from disk.
• Some code simplifications in IntervalModel
• Remote control protocol now knows when an interval is being paused / resumed.
• Control surfaces send more information through remote control protocol.
• Fix bugs various bugs found since a25 was released.
• Fix a bug with offset and scenarios with graph intervals.
• Pure-Data plug-in: look for Purr-Data if available as editor.
• Pure-Data plug-in: add an API to create UI controls in [r].
  See the documentation: https://ossia.io/score-docs/docs/advanced/puredata.html