DOC: mention new comparison runtime warnings in release notes
DOC: move support for large files to features

its nothing you should need to worry about when porting to 1.8
DOC: update percentile release notes and add np.array improvement
DOC: minor rewording of partition note
Merge pull request #3841 from juliantaylor/rnotes-master

update 1.9 release notes and sync 1.8 notes with maintenance branch