added link to additional issue for old blackouts
added #787 to changelog retroactively
preliminary addition of v4.0.0 changes to CHANGELOG
added #781 to CHANGELOG
added missing '#'
Merge branch 'master' into 849_v400_changelog

Includes v3.4.6 and v3.4.7 updates to CHANGELOG

Conflicts:
	CHANGELOG.md
Merge pull request #1001 from YaleSTC/849_v400_changelog

resolves #849