Python routine boutdata.restart.create

Creates a set of restart files from data (dmp) files,
optionally averaging over a number of time-points.
Two main uses:

1. You want to start the simulation from a time for which you don't
   have a restart file. You might need to adjust parameters or resolution
   (in which case other routines are needed to resample the data)

2. You want to find a steady-state solution, and want to damp out
   transient oscillations by running for a few periods, averaging over
   a few periods, restarting and repeating.