FESOM/fesom2: Control forcing and IO from namelists. Initial CVMIX implementation.

I/O control has been added via namelist.io.

The format for a new entry is:

    ('name      ', frequency,  frequency unit, precision). 'name' shall consist of 10 symbols. Add blanks if too short.

In order to add a new variable as a stream you need:

1. add this to namelist.io
2. modify io_meandata.F90 accordingly as it has been made for other variables.

Add FESOM interfaces for CVMIX-TKE(Turbulent-Kinetic-Energy) and IDEMIX (Internal-Wave-Energy) vertical mixing parameterization. Still needs to be fully tested, but so we can unify the Infrastructure for CVMIX

The new way to define atmospheric forcing for FESOM2. Now one can use a namelist.forcing to provide pathways to forcing files.

• Some colorful screen output to highlight important things.
• Fix a bug regarding max limiter of GM coefficient
• Layerwise I/O for restarts and meandata.
• Unify restart for zlevel and zstar.
• Floating sea ice to zstar and different EVP schemes.
• Change the default scheme to calculate pgf to shchepetkin.
• Actualize and restructure routines for calculating the pressure gradient force.
• Fix bug for zlevel and zstar (but also a bit for linfs) in how to balance the fresh water flux to the ocean and to avoid the ssh of drifting away.
• FIX MINOR BUG WITH MAJOR IMPLICATIONS FOR ZLEVEL AND ZSTAR. This bugfix makes zlevel and zstar finally as stable as linfs and solves partially also the issues regarding the boundary current.
• Tested functionality of partial bottom cells for the linfs case, performs at the same time step like the full cell case, different options to calculate the bottom pressure gradient force in case of partial bottom cells are available.
• Timings for setup, output, and diagnostics added.