eTAOC fixes

[esclapez]

• add options to indicate amuse/omuse restart data:
  • "amuse_restart", where both old and new state data are specified through amuse copy into POP arrays. Initial Euler step is bypassed.
  • "amuse", where a single state data is provided and an Euler step is required upon starting the simulation (coming from i-emic data for instance).
• store the last restart file written to disk.