Prepare for release of 2020.10.1

Merge pull request OPM#6812 from OPM/dev

Release 2020.10.0

Merge branch '2020.04-patch-01'

LibEcl : Add missing include for latest VS2019

Merge pull request OPM#5422 from OPM/2019.12-patch.01

Patch release 2019.12.1

Merge pull request OPM#5253 from OPM/release-2019-12

Release of 2019.12

Merge pull request OPM#4758 from OPM/patch-2018.08.2

Patch release 2019.08.2

Set version number to 2019.08.1

OPM#4636 Curve Data Export : Use correct column header for P10/P90

Merge pull request OPM#4382 from OPM/master

Merge pull request OPM#4381 from OPM/dev