Sync velocities to output time when calling Velociraptor
When we call Velociraptor the particle velocities are not extrapolated to the output time (or I can't see where it happens). Is there a good reason not to do this? It appears that the velocities written to the snapshot are extrapolated but we don't use those values for the velociraptor call.
Here I've tried to implement the extrapolation by just calling the same functions from gravity_io.h which are used to write the snapshot.