Lammps multistep

Open username-removed-580823 requested to merge Mazay0/ase:lammps-multistep into master

ENH: Implemented Multistep usage of LAMMPSrun calculator. Multistep means that LAMMPSrun do not read/write atomic coordinates after each step of molecular dynamics or minimization procedure, but multiple steps are performed by LAMMPS itself. It significantly speeds up calculations but user have to specify all system constraints as LAMMPS parameters. Tests of typical use cases added. There is a need of this functionality: