[Opm] 2020.04 release - it is for real

[Joakim Hove]

Dear opm-community;


we have now completed the the new 2020.04 release - binary packages for 
RedHat and Ubuntu avaliable as described here: 
https://opm-project.org/?page_id=36

As usual there has been a myriad of fixes and improvements since the 
2019.10 release, but some notable points include:

 1. Major improvements to the group control capabilities.
 2. In mpi runs the initialization is only done on one node,
    significantly reducing memory consumption.
 3. The parser now recognizes all Eclipse100 keywords; for the keywords
    which are recognized by the parser but not really handled by the
    simulator a warning well be printed.

Thank you to people who have tested - and Arne Morten for building the 
packages.

Go and simulate!

Joakim