Truncated .dat file from HOS

endtime in modesHOSswense.dat files is implicitly assumed to be the duration of the HOS simulations. However, it might be possible that the HOS simulation is stopped while running and consequently the .dat file is uncomplete, which will cause an issue in Grid2Grid reconstruction, that might be difficult to track.

Then in the initialization of Grid2Grid, it should be possible to test the integrity of the file to see if it is 'complete'. If not, either modify endtime, either return error message.