Feature hybrid coord2

[milicak]

CVmix mixing scheme has been added for the hybrid coordinate.

[matsbn]

Looks good, although the mod_vcoord.F90 changes are unrelated to CVMix and makes the commit message confusing. I'll approve anyway and maybe revert the mod_vcoord.F90 changes afterwards and commit with appropriate message.

[TomasTorsvik]

Looks good, although the mod_vcoord.F90 changes are unrelated to CVMix and makes the commit message confusing. I'll approve anyway and maybe revert the mod_vcoord.F90 changes afterwards and commit with appropriate message.

@matsbn @milicak
I think it's much easier to make changes before something is merged with the main repository than to fix it later on. This sometimes cause a confusing commit history. Unless it is really urgent, I would suggest to take the time and fix the pull request before merging.