Migrated from use of 'INCLUDE mpif.h' to 'use mpi' as that is preferred for modern Fortran; Trimmed commented old code

Fixed dilatation rate calculation, added option of using 2D strain rate invariants and removed some commented lines

Removed passing of call_cnt for debugging, extra debugging output, added option of using 2D strain rate invariants and fixed Mohr-Coulomb plasticity formatting to be similar to the other options