THM: sensible heat element-wise output.

Computation and output of sensible heat (w/o latent heat) element-wise.

The computation of total sensible heat especially with freezing (latent heat) is awkward and inexact in post-processing.

Verification on benchmarks without and with freezing: w/o freezing the verification with constant density and other properties is simple, w/ freezing the latent heat must be reconstructed. See attached python script: verify_sensible_heat.py

1. Tests covering your feature were added?
2. Any new feature or behaviour change was documented?

• Add this merge request to the changelog