Add trajectory reloading

[BradyAJohnston]

Fixes #615
Fixes #614

Helps to fix errors where the trajectory loses it's connection to the underlying universe. Adds operator to more easily restore the trajectory when the connection is lost

blender_KEOUSOHU79.mp4

• Operator to reload trajectory
• fixed problem with pickling while saving

[CeraveWasTakenLOL]

Just curious, does this reset the entire geometry node system? If so it might be advantageous to add a manual caching system for the MNSession

[BradyAJohnston]

@CeraveWasTakenLOL this doesn't change anything about the Object / Geometry Nodes setup (so any keyaframes etc will be maintained) it just re-links the underlying MDAnalysis.Universe so that the positions update on frame change

[BradyAJohnston]

@CeraveWasTakenLOL also there is a Bake node inside of Geometry Nodes so if you are wanting to bake & create a permanent save state of the trajectory you can use that node to bake the positions to disk (in Blender 4.3 it will be able to bake into the .blend file)