[MITgcm-devel] Update reference machine

[Jean-Michel Campin]

Hi,

We are going to update (very soon) the "reference" platform,
from the old "baudelaire.mit.edu"
    running: FC-13 (2.6.34.7-61.fc13.x86_64,from 2010) with gfortran 4.4.5
to the new   "villon.mit.edu"
    running: Ubuntu 18.04.3 LTS (4.15.0-64-generic, from 2019) with gfortran 7.4.0
This is the  purpose of PR #290.

The motivation for switching to Ubuntu is that it's a Linux distribution that
is popular (and many users are likely to be able to access one) and is "Long Term
Supported" so that it's easier to maintain without frequent significant upgrade.

I am going to make a tag before merging PR $290.

Two comments:
 1) Currently, there are very few developers that have access to villon ;
    we could certainly add few more, depending on the need, either with MIT kerberos
    login or with ssh-key.
 2) OpenAD does not build on any new system (including "villon"); it has already been
    a problem for sometime with recent FC releases ; but we cannot hold on any
    update just because OpenAD is lagging behind. There are still some OpenAD
    testreport that will be run daily (by Oliver on engaging) but not sure how long
    this will last.

Cheers,
Jean-Michel