mf_dft_water

Cosmetic changes to variable names

corrected calculation of microscopic stress. Avoiding laplacian usage through analytical calculations

Added derSigmaXZ, derSigmaYZ and derSigmaZZ to the output

modified version of the p0: now it is just a "single phase" pressure

Switched to calculation of density from the field file. With respect to the values from the snapshot, it has much greater accuracy (12 digits after coma vs 4). Getting smoother data.