lammps crashes without exception

[nathanfranklin]

If an error occurs in the lammps library (e.g. using lammps.py etc), the process immediately exists (without an exception). The current Lammps library (written in c++) just prints out an error message and returns a non-zero exit status (i.e. exit(1) ) when an internal error occurs.

[nathanfranklin]

We have to evaluate changing this so an exception is thrown that is seen by the python-lammps interface and ultimately SimPhoNy.