planned changes to geometricVoF

As hinted in issue #1955 (closed), we (@johan_roenby and me) are planning to update the geometricVoF code and unify it with our open-source release:

https://arxiv.org/abs/2103.00870 https://github.com/DLR-RY/twophaseflow

This step will significantly reduce our time spent maintaining both codes and should raise the code quality of both releases. This would also signficantly simplify testing the library for us.

Currently, the libraries are almost identical and the only feature added is the capability to run interIsoFoam with AMR. In this process, smaller changes to the comments are also planned.

Would you support this approach?

if so, I would create a new branch so we can merge into develop later @kuti @andy @mark