Moved compute_plastic_params subroutine from vrm.f90 into a separate file. It is no longer called by DOUAR as it was not doing anything unique. vrm.f90 handles all of the plasticity parameter calculations now.

Renamed minp as plastic_stress_min to be more accurate; Modified echoing of input values to follow order given in input file

Replaced ztrans functionality for material transitions below a given depth to a more general transition behavior which allows transitions in at any constant x, y or z value

Modified pressure0 to be converted from positive to negative from the input file, consistent with the DOUAR pressure sign convention