#2737 update changelog

Merge pull request #2501 from stfc/2447_release_2.5.0

(Closes #2447) Create release 2.5.0

Merge pull request #2339 from stfc/2108_release240

(closes #2108) release 2.4.0

Merge pull request #1761 from stfc/1760_release_2.3.1

(Towards #1760) release 2.3.1

#1728 update changelog

#1640 update changelog and UG for 2.2 release

Release 2.1.0

Release 2.0.0

pr #752. Created tag for release 1.9.0

issue #609. Tagging release 1.8.1