get dimensioning from output file in case Atlantis run doesn't finish

[sgaichas]

At present, the total number of timesteps for atlantisom is taken from the run.prm file.

This works if the run actually finished.

However, if an Atlantis run didn't finish, then the dimensions for the full run will be incorrect.

Therefore, consider reading from the BiolInd.txt file last step to approximate the actual timestep at the end of the run.