ChangeLog: Added changes from v2.6.0 release that are mentioned in commits
git log v2.6.0-master.. | grep 'FIXED:\|ADDED:\|UPDATED:\|CHANGED:\|REMOVED:' | sort
Applied minor corrections: letter cases and spaces.
ChangeLog: fixed spelling and punctuation
ChangeLog: Added manual updates caught by browsing git history
Updated NEWS with highlights of v2.7 release and a note for previous releases
Updated Features page with highlights of v2.7 release