T-dependent heat capacities #4778

Hi there. I have been using Modelica for plant modeling on a few projects over the years and thought that i contribute some new features here and there. One of which would be temperature dependent heat capacities in the Thermal library. As a first step i put together an initial implementation of the Debye function (pull request #4769) for the purposes of such modeling. I have more functionality ready to go (the Debye EoS and heat capacitors). I was just wondering if this was of any interest. I look forward to discussing this possibility further, either here or in the comments to the pull request.