[feat] Music/Sightreading mode

[KorigamiK]

I would love to have something similar to what okular provides and build upon the functionality.

If you want to read a document with several pages use the automatic scrolling feature of Okular. Start automatic scrolling with Shift+Down or Shift+Up. Then use these keys to increase and decrease the scrolling speed. You can start or stop automatic scrolling temporarily by pressing the Shift key; pressing any other key deactivates this feature.

Having this helps in reading music while scrolling through the pages automatically.

Functionality required are

1. autoscrolling
2. adjusting the speed of autoscrolling
3. cropping the margins of the pages (odd and even)
4. Visual Highlight / Bar indicator similar to musescore

Let me know how I can create some of this functionality through the scripting api introduced if possible.

Would be glad to help in developing them as well, cheers!