Add multiframe feature to style

[satary]

Hello Brady! Thanks for the great addon!
I wander if it is possible to simultaneously show several frames from a trajectory or a multi model structure. This is very handy for NMR ensembles and MD trajectories.

Thanks,
Grigoriy.

[BradyAJohnston]

Hello! This is discussed a bit in #362. It's possible to do if the trajectory is loaded into memory and animation through the frames are done through the node tree. You can use a 'Repeat Zone' to create a style through multiple loops, changing the frame that is chosen each time.

It seems that there is interest from people for a easier solution to this, so I'll try and make a node to include. Unsure how it might work but will have a play around with it.

[satary]

Thank You! That's neat!