Recreate a Recreation

[Laurie Nevay]

Make it possible to recreate a recreation. Currently the use of options and event offsets internally prevents this.

For example, original simulation has 100k events in it and we have an output file. Recreate from say event #54321 for 10 events and store in new output file. Now recreate this recreation starting from event 2 in that file.

This should also work when the original model used a userfile bunch distribution - ie the we have to look 54321 + 2 entries into the bunch file, but ultimately the ID of the event is 2.

Currently, we try to advance to event 54321 but this is beyond the 10 events in the 1st recreation file, so no seed is loaded.

Perhaps a Boolean in the options or header to note whether this file was a recreation. Maybe also cumulative bunch offset.