Add Lammps_run to the calculator

[qzhu2017]

Currently, we support lammpslib. However, it is sometimes no easy to install python-lammps. Here we provide another calculator similar to lammps_run so that it can be called from system.

[qzhu2017]

• Single point energy calculation

• Optimization

• MD simulation (NVT, NPT)

• Read Structure/Energy/Forces/Velocities/Stresses